Yeah, they're pretty cheap. I'd like to make my own for many reasons. Experience, Multiple inputs, etc. I never made one(that works) and just want to try it out. Might as well do a really nice one while I'm at it. I'm going to make three input types with a nice audio filter, also mutiple power supply types, 12V, 9V, and 120VAC. I could do all that with a store bought one, but where's the fun, and gratitude.
I always see websites with lots of transmitter designs that are pretty similar. Most the cheap premade ones aren't any better then a 2 dollar homemade one. I don't really want one of these that bad, it comes down to just wanting to have a better understanding of how, and why it works. That might give me a jump for next term in school too, if not, it would still be neat.
Edit: is Blue Room Electronics your site? I've been eyeballing the mongoose kit for my son when he gets older.