a friend of mine is sellin a rx7 wont let me go in to1st 3rd or 5th what do you think is wrong with it. is it wroth 3grand to buy

 

Needs to be rebuilt. Probably wasted synchros. I wouldn't pay 3k for the car, you're going to end up spending about $1500-2000 having someone remove/rebuild/reinstall it.

The cheap route is to get a used na tranny and switch it yourself, but that's not for everyone (would only cost you a few hundred), and you run the risk of having the replacement die on you as well.

A 3rd option is a TII tranny and custom driveshaft.