Hold up on that trans rebuild. Be reasonable to yours and start researching trans builds. You'll come across TripleEdgePerformance.com and a few other tidbits at you learn. I always suggest reading and reading and asking questions ....then saving for a build.
Learn what you want and need before jumping into it. My first trans build was right around $3500...that one got rebuilt about 5 times in 2-3 years. Then I built another (right, everyone should have two race built transmissions) and that held together for about 3000-5000 miles. Actually pretty good for my average mileage between issues. Not saying my experience is "normal" however you sound like you may enjoy driving in a similar fashion.