Yeah, I'm leaning towards at least a 5g tank. My parents are afraid of letting me get a tank in case I don't properly take care of the fish and it dies on me, but I believe I've read enough in order to properly take care of a Betta, at least. Even if I can't start off with a larger tank, though, I'll be sure to take great care of my fish. That way even if I start with a smaller tank, I may be able to convince my parents that I'm able to take care of a whole tank.
My mom has had a twenty-gallon tank in which we've housed goldfish for years, but I don't believe she's ever cycled the tank. Some of the fish have lived for over ten years in it. Is this because goldfish are hardy? Would not cycling a tank first kill my Betta? If cycling is in fact necessary, what would be the quickest way to do it?
Thanks again everyone for the help. I'm also so glad you have convinced me to try and get a bigger tank. Now I feel so bad for ever wanting to put my Betta in a gallon jar.