New trucks aren't all they are cracked up to be. Purchasing a new truck now is a second mortgage. I will stick with my old truck, fix/repair/rebuild what needs to be done and not have a huge payment every month. To replace the truck i have with a new one would be north of $70K. No Thanks. Get your's fixed and drive it.
$2100 isn't bad for a transmission rebuild. I had a recommended "builder" from a friend of mine do my trans. Well, it blew up 400 miles from home with less than 3k miles on it. I have it at a reputable shop and the parts alone right now are at $2k.
Good luck and hope you get it repaired.