To "节约一切资源" about your bad trany

You did not state what's exact symtoms. Also I am not that good to know where exact problem is. Maybe that is not important since I do not think you can rebuild it(sorry). If you ask shop to do it, it's not worth it for sure no matter where it's wrong.

Here two options.
1) buy a used one trany and it should cost $300-500. install it by yourslef. Or ask a Mexican guy to install it for you. may cost another $200-300. In some cases, you just need replace torque converter, but it's difficut for you to diagnose it. so just pay a whole trany.
2) sell it through craigslist.com. There are so many Mexican guys who are searching cars that have problems. You should receive many calls within 5 mintues. sale price should be based on this. Let's say your car worths $2000 if it's not broken. You should be able to sell it for $1k in your case.