Wow, this is getting to be one of the most frequently asked questions on DSMCentral. DSM transmissions...go figure!
Slo-Pny has been rebuilding DSM transmissions for $150 labor plus what-ever parts you need if you take out and deliver the transmission. A new set of synchros costs 'Roughly' $150. You can obviously price out all the TRE stuff yourself.
My motto is if you've got the money, beef up what you can. In reality I've been able to get away with stock shift forks and rails. I really enjoyed my GVR4 1st gear untill it grenaded on me after about 75 WOT launches in 3 months. Since then the stock DSM AWD 1st gear has worked great for me.
Hardening from Fast Forward would be my next way to add money to the pit if I were going all out. Shift forks have gone out right in front of my eyes, so that would be my first conservative step. The stock forks should be adequate as long as the synchros are letting gear changes slide smoothly though.
Let us know if you need anything...