I'm a bit late to the thread. Here are my 2 cents since I am a dentist in TX with my own clinic btw.
For implants, take your time to find a good specialist. Mexico is definitely cheaper because of the cost of living, currency exchange, and different education requirements (more in US). There are good and bad docs/clinics in both the US and Mexico. Wherever you choose to get it done, you will pay with either time or money, or both.
One important thing to note for OP since he didn't mention which teeth got knocked out and what the oral condition was: It's important to budget for extras because in addition to the implant (which is just the titanium screw), there are other things which may be needed such as x-ray, surgical guide, abutment, crown, bone/gum graft, etc. There are tons of clinics which may advertise "low priced implants" to get you in the door, but then hit you with the other fees, classic bait-n-switch.
There are several well known brands of implants with reputable 10-year success rates used in the dental community. I would ask:
1: which style/brand he plans to use (many clinics use cheap material to increase profit margin)
2: if he is doing immediate-load or traditional implants,
3: final prosthesis selection (which lab vs CEREC),
4: how you will be monitoring post op and implant success,
5: treatment alternatives (bridge, partial denture).
The road to success with the implant is more than just placing it. It requires osseointegration and careful post op along with the finalized prosthesis. That is one of the issues with doing it in a different county. Anyone can place it, but sometimes it fails and no doc in the States will touch it for post op, at least not for free. If you want some advice, let me know.