rebuilding a t-5

You only have a few options.
rebuild upgrades:
gforce t5
Astro performance T5

Completely new transmissions:
Tremec tko 500 or 6000
T56
All of which are going to cost you about 2500 to get setup, except the t56 according to D&D performances site, you are looking at 4 grand to setup a t56.

It all depends on what you are doing. Any way you go you will spend money on this. The only cheaper route is to rebuild what you have but thats not all that cheap to do plus like you said it will only last so long before it happens again you will spend more money in the long run then getting what you want the first time.

The astro or g-force gear sets will be around $1200. Plus a clutch and other miscellanious things. It cost me $1600 total to do the Astro gearset in mine with the clutch and everything needed, rebuilding it myself. Yea, it's a lot of money to spend on a t5 but it's been putting up with a lot of abuse for over 10k miles now, and it shifts like butter. We'll really put it to the test next season.

You could do one of the heavier duty t5 gearsets that are rated at 330ft lbs. I believe they can be found for a couple hundred bucks on ebay. Do a 26 spline input shaft while you're at it and a steel bearing retainer. Rebuild it yourself and you'll be under $1k all said and done and it should be pretty rugged.

A lot of people consider T5s garbage but I've seen rebuilt ones take some beating. Nothing is lighter, and no syncro tranny shifts smoother. Syncroed tremecs are dificult to powershift, especially in higher rpm.

If you are considering rebuilding a t5 yourself, be 100% sure that you know you can pull it off, if not, you will up with 100's if not thousands of dollars of scrap metal.
Home trans rebuilding is not for everyone.

The trans in my car is an Astro-built T5. Its not their "A5" gearset, but its an upgrade over the stock WC T5s. I believe it is rated for 350hp. After I sent them my broken T5, I think it only cost me 700 bones, but I believe their prices are higher now- this was a few years back.

Rebuilding a T5 really isn't that hard if you have a good reference (book/video) and the right tools. The most important thing is to remember is a new or rebuilt unit needs a break in period just like rear end gears do. I rebuilt the T5 I had before the Astro unit, went out and started slamming gears as hard as I could without even letting the engine warm up, let alone the transmission wear in. Needless to say 10 minutes later I had an 80lb paper weight.