Vox quotes economists that the US health care prices per item are abnormally high. So other countries get more health care for less cost:
"When you’re paying the highest prices in the world for basic services, for scans and drugs, it will undoubtedly be a struggle to provide all citizens with health care...

• Americans go to the doctor four times each year.
• Dutch people go to the doctor, on average, eight times each year.
• Germans make 9.9 annual doctor trips.
• Japanese residents clock in an impressive 12.8 doctor visits each year — more than three times the frequency of their American counterparts...

When Americans do go to the doctor, we tend to have less face time or interaction with our providers.

• The average hospital stay, for example, is 5.4 days in the United States.
• This puts us roughly in line with New Zealand and Norway (5.2- and 5.8-day averages, respectively) and with much shorter stays than Canadians (7.5 days) or Germans (7.8 days).

The real culprit in the United States is not that we go to the doctor too much. The culprit is that whenever we do go to the doctor, we pay an extraordinary amount."

​DailyKos has more detail on the range of costs.

• "America’s economic competitors discovered years ago and still share today... Whether negotiated directly or through a national association of insurers, the government sets the prices for prescription drugs, tests, treatments, hospital stays, and pretty much everything else...
• Economics, after all, is the study of the allocation of scarce resources... In the face of the infinite “wants” for healthy citizens, financially secure families, well-compensated practitioners, and strong profits for private companies of all stripes, societies must choose how and why to distribute discomfort and dissatisfaction to some or all of the constituents."

​​And DailyKos quotes the Commonwealth Fund comparisons:

Puerto Rico and Maryland are exempt from readmission penalties, and are still covered by Medicare. Links for Puerto Rico are below.

Foreign hospitals and doctors have their own payment systems for their residents, but still have prices for US travelers. They are not covered by Medicare, so hospital stays abroad do not incur readmission penalties, and do not count as costs in Accountable Care Organizations. Some US and international private insurance pays for foreign care. In any case costs are often much less than in the US, and specialized hospitals can give better care. Some of the best offer luxury as well as ordinary care.

Lists

• One list of top 10 hospitals, 2014 (bones, cancer, children, hearts, hernias). Best is in Maryland. 7 are abroad:
  Asklepios Klinik Barmbek, Germany: Drugs, Equipment, Laboratory, Heart surgery, Cancer
  Great Ormond Street Hospital, UK:  Children, Children's heart or brain surgery, Children with cancer
  Wooridul Spine Hospital, South Korea: Spine, Joints
  Shouldice Hospital, Canada: Abdominal hernia
  Bumrungrad International Hospital, Thailand: Most specialties
  Anadolu Medical Center, Turkey: Cancer, Bone Marrow Transplant Center, Preventive medicine
  Gleneagles Hospital, Singapore: Orthopedics, Cardiology, Cancer, Obstetrics, Gynecology

• Deloitte estimated in 2008 that 750,000 US residents went abroad for treatment in 2007, and about 400,000 foreigners came to the US for treatment. 28% of Medicare recipients would consider elective surgery abroad, with higher rates among Asians and Hispanics. Their 2016 report says Thailand and Mexico are the top destinations, and they expect growth in Cuba now (p.15; their footnotes are in a separate file). The 2008 report lists top foreign hospitals with their specialties as
   Bumrungrad, Thailand: Orthopedics, Neurology, Plastic surgery, Dental, Cardiovascular, Cancer, Fertility/sex reassignment
  CIMA, Costa Rica: Orthopedics, Neurology, Plastic surgery, Dental, Cardiovascular, Cancer
  St. Luke's, Philippines: Orthopedics, Neurology, Plastic surgery, Dental, Cardiovascular, Cancer
  Apollo, India: Orthopedics, Neurology, Plastic surgery, Cardiovascular, Cancer
  American, UAE: Orthopedics, Weight loss, Cardiovascular, Cancer, Fertility/sex reassignment
  National Cancer Center, Singapore: Cancer
  Ivo Pitanguy Clinic, Brazil: Plastic Surgery 
• Joint Commission International accredits hospitals abroad. Founded by Joint Commission in US, which is a separate organization.
• Awards, 2015 were based only on written applications by the hospitals and €150 fee from each contestant

Referrals

• Subsidiary of Blue Cross (surgery and dental), includes the Costa Rican, Indian, Thai, and Turkish hospitals listed above. See their cost data below.
• WhatClinic.com has a few reviews worldwide, for example 16 reviews of knee replacements, and 8 of hernia repair (none from any hospital listed above). Reviews can be found with a specific term, like knee replacement, but clinics describe themselves with broad terms like orthopedics, so search both ways. It probably needs to partner with local review sites to get more reviews. Reviews are mostly accepted from people who had previously contacted the clinic through the site. They do not mention a policy on removing reviews. Clinics can list themselves free, or advertise.
• Medigo.com lists many hospitals and clinics for many conditions in many countries. Among the hospitals recommended above, Medigo only includes Apollo in India. The lists are easy to search and often give prices. They do not rank clinics on quality, and do not describe their criteria for listing clinics. They do not visit all the clinics, and they say when they do. The few patient ratings only appear on each clinic's page, so comparing ratings is a slow process. Terms of use forbid "disparagement" (8.2), and they do not say whether they include all reviews. They charge 0-9% to arrange treatment, depending on country, and various other fees. You can search with their free lists and contact the clinics directly if you don't want Medigo's services, but you'll need to find other measures of quality. They cite news stories, which cover medical tourism, not Medigo. Terms of Use limit their liability, and section 9.6 makes you pay their costs for some lawsuits. They are based in Germany, and the founders are Polish. Suits against them must be in Berlin.
• Dental Departures (dental referrals and travel agency) visits nearly all their dentists, has questionnaire on sterilization, includes patient reviews, and has dropped 8 dentists for poor quality from its list of 2,500 dentists in 29 countries.
• International Association for Medical Assistance to Travelers (designed for people who get sick abroad) has a directory (for a small donation) of English-speaking doctors in most countries who will see you for an initial consult of $100. These provide a chance for checking the local reputation of a surgeon you are considering, or treatment of follow-up complications. "majority has received post-graduate training in North America or Europe... IAMAT health care providers will refer you to a specialist in any field, including dentists... Our doctors and mental health practitioners will advocate on your behalf and help you with any issues that may arise during your experience with the health system of your destination country."
• Medical Tourism Association (industry association) See their cost data below.
• Patients beyond Borders (medical travel agency), lists other articles and questions to ask your doctor
• Planet Hospital (medical travel agency), lists other articles
• Pilgrimed (medical travel agency) See their cost data below

Advice

• Organization for Safety, Asepsis, & Prevention suggests phone questions to ask foreign doctors; has members abroad
• Aerospace Medical Association, risks of air travel with some medical conditions

• Centers for Disease Control (advice) says some countries have poor quality drugs, more resistant bacteria, and paid blood donors, without saying which; links to other organizations
• American Medical Association, 2008 recommendations on foreign care. They say patients should get "physician ... outcome data" (p.6 line 48), which is only sometimes available in US
• International Society of Aesthetic Plastic Surgery advice; has members abroad

Articles

• Buzzfeed, 2017, on hundreds of dentists in Mexico near Yuma, and using RV community for referrals
• US News+World Report, 2012
• AARP, and US News+World Report, 2014, by same author
• Economist, 2014
• Guardian, 2014, on Poland

Other

• Puerto Rico 2013, updates: 2014, 2015, 2016, covered by Medicare, exempt from readmission penalties
• Maryland, covered by Medicare, exempt from readmission penalties, working toward new limits by 2019

NA=US Average not available to calculate percent. See link for costs abroad