If you are going to be making recordings and are on a limited budget, Audacity will do the job. A few important things though, get a decent microphone, try to position it so you don't breathe into it, and practice your lines. Also, and this is just a pet peeve of mine, most people "pop their p's" when they speak into a microphone. This happens because you are using too much air to produce the sound most likely because you are trying to be louder than you need to be. Just speak normally and do many takes of each segment till you get something you are happy with. Lastly, don't be afraid to get some of your friends to listen the (semi)finished product while you are producing it and ask them for feedback on how to make it better.
As far as comparable programs, the big one seems to be Sony Vegas, which usually runs about $500 to $600 USD.