I can rebuild transmissions... I'm not going to install them though - you'd have to bring me the transmission out of the car. How much you will spend on parts depends on what your tranny needs and what you want to replace while you are at it. You can buy rebuild kits for about $300 that include the main and diff bearings and regular brass synchros. Such a kit does not include synchro springs ($50/set) or needle bearings (~$15/each and there are 5 in the tranny) or synchro sleeves. Carbon synchros are $150-$200/ set. Synchro sleeves are about $100/each or you could get a 3rd and 4th sleeve with the 3rd and 4th syncrhos for about $200.

I currently have a B16 w/ LS 5th for sale for $450 that is in perfect condition (I'll take a grinding YS1 GS-R tranny as a partial trade).