Depends on what you mean by "average to decent' ???

I would say the difference ranges from being more than twice the cost if comparing it to a large private non-profit hospital, to being say 10 - 30% more if comparing it to a large private hospital in Bkk other than BNH/Samitivej/Bangkok Hosp. For those last 3, all in all it averages out to bout the same more for some things, less for some others. Not suprising since these 4 are all owned by the same parent company.

Also depends on the specific doctor you see (doctor fees are individualized) and the procedure that is done. And, if you are talking about inpatient care, it will depend on the type of patient accomodation (room). All admitting offices try to persuade you to take the most expensive room they can, even the non-profits do this, and they will often not even acknowledge that less expensive options exist until you insist on it.

The cost difference in comparison to a government hospital or military hospital is enormous..ten fold or more in many instances, even allowing for getting a private "VIP room" at a government hospital. In fact, if you are talking about inpatient care, you can get a private "VIP" room and private duty nurses round the clock at a government hospital and still come out way ahead. For surgery and other inpatient care, and providing you stick to large tertiary-level government hospitals, this is an option well worth considering for the uninsured. There will be a fair amount of hassle/red tape (all of it in Thai language only) in arranging for admission, but once admitted it's not at all bad.

For just an outpatient visit, unless you have far more time than money and are prepared to spend a full day in hot, crowded, unpleasant conditions trying to navigate a complex buearacracy where all signs & instructions are written only in Thai to save say 1,000 baht...it's worth the money to go private.

regarding the visa, Bumrungrad (and probably the other big "international" hospitals) does have a department which can help arrange things with immigration, and there are special provisions in immigration law for medical emergencies. but do not be surprised if a charge for having done this shows up on your bill.

If you dig deep into Dr. Mason's credentials you will find that he is a rotator cuff specialist and studied with one of the best rotator cuff surgeons in the US at Mass General which is an excellent hospital. I have a close friend who had shoulder and knee surgery with Dr. Mason and found it all to be a great experience.