Well you could just make a really hard rubber substance for the tires and it would be cheaper than kevlar and last forever, BUT the harder the tires, the less traction that you will get. If you're going to start racing, I think you really need to go to the track that you're going to be racing at, and talk to the guys racing about their tires. Chances are most of them are going to be running similar tires because everyone wants that edge and they're all going to be running the best tires for that particular surface. The clay that's on my home track and the clay thats at the track at the LHS is completely different, so you can imiagine how hard it will be for someone across the country to guess what tires you need. Something else that you're going to want to decide is what compound to run. You can run a harder compound and get a couple of races out of a set of tires, or you can run a softer compound and get more traction but change them after each race.
So how's that motor holding up for you? I kinda regret selling it now, but I'm so glad that you're enjoying it. When you go to the LHS, find out the class rules for racing at your local track. That cobalt revolution motor may be too big for the mod class and you might not want to start racing in the open class. If that motor is too big, I have a Reedy 17 turn motor that came with my stock T4, and I'm sure it will fit better in one of the classes at the track. If you need it, I'll sell it to you for almost nothing since you bought the other stuff from me.