Verifying credentials & facilities in Mexico... Any suggestions?

You need to check on the American Board of Plastic Surgery to see if your surgeon is Board Certified by this particular Board. If you would like to check if your Surgeon is Board Certified in Mexico, check the web site of the Consejo Mexicano de Cirugia Plastica, Estetica y Reconstructiva. If you want to check what facilities are approved in Mexico, you will need to check the web site for the COFEPRIS that regulates the hospitals and clinics in Mexico. Also you can check the AAAASFI that is the American Association for Acreditation for Ambulatory Facilties International.

Dear mizzf thank you for your question.
The CMCPER (Consejo Mexicano de Cirugía Plástica, Estética y Reconstructiva) is the only board approved by the Mexican government to certify that plastic surgeons are fit to do aesthetic and reconstructive surgery. You can go to their website and find every certified plastic surgeon in their directory. If your physician is not in that directory then he or she is not a trained plastic surgeon, and by law should not be performing any kind of surgery.
As for Hospitals or clinics the Consejo de Salubridad General is responsible for Certifying that institutions comply with national health standards. You can fin affiliated institutions in the supporting link

The simple answer is you can't. There are many doctors that will claim they are "board certified" by various cosmetic surgery boards that often require no more than them making a payment to obtain a certificate. When it comes to considering surgery on your body, it is not an area you want to compromise to save money. Another important part of your surgery is the follow up care afterward. Many surgeons in the US will not assume your followup care and if a complication does occur, you will still be responsible for that financially. If you wouldn't go to Mexico to buy a used car, why would you go there to have surgery?