Yes, You can pay the $4500 peso overstay fee at the bank at the airport. If I understand correctly, the procedure is as follows: first you get a paper from migraciones, then pay the fee, then return to migraciones, and then check in for your flight. It is quite routine and nothing to worry about.I just wanted to make sure please-I got here October 12th and have to go back to the States for work on January 26th (I will plan my residency after). So I can just show up at the airport even if I'm 14 days over and just pay a fee?
You should go to the airport at least a couple hours earlier than you normally would.If anyone reading this thinks you should go earlier than that I hope they'll post about it.I will still be able to leave and catch my flight?
Be sure to pay the fee even if the airline employee who checks your ticket and your passport .before you're allowed to get in the check in line somehow misses the fat that you have overstayed your 90 day visa.
PS: The "overstay fee" is different from the 90 day "prorroga" that was mentioned in the post you quoted. The latter costs $2700 pesos but there is no reason for you to go to migraciones to get a prorroga. You will be paying the overstay fee at the airport.