You got scammed. There's no way in the word that a VSG would cost that much and especially since you only spent one day in the hospital. In my state it's about $16,000, self pay. The average seems to be $25-$30,000.
I'll be going to Tijuana as well but I haven't settled on a doctor. I'm hoping to have mine toward the end of 2015, or as soon as I can save up enough. I want to fly first class and have enough spending money in case they charge you for some things that you may not be aware of. For example, some doctors include the meds in the price and others do not. Plus many coordinators take the patients shopping there and I want to buy stuff as I may be the last time I got to Mexico. Good luck!
Will you be staying in the Marriott? I would love to but the coordinators I've communicated with use other hotels.
I quit smoking a year and a half ago using e-cigarettes. I know that many doctors won't perform the surgery if you smoke but what about e-cigarettes? The reason why I ask is that they don't have any of the horrible chemicals and tar that cigarettes have. They still have nicotine but nicotine is about as bad as caffeine. I was really thinking about just telling the doctor that I don't smoke, which is technically true, and then sneaking in a small e-cig with me.