Thank you very much for your replies. They have really helped!
I would like to play french music that is kind of jazzy. The particular music that I want to play comes from Disney's Ratatouille soundtrack. I am not sure wether they used an accordion or a concertina, but I like the look of the concertina better. The music is mostly melodic, and it doesn't use harmony or chords all that much. So, now that I think about it, the English might suit me better.
I am fifteen years old, and my resources are limited. In my search for a good, inexpensive instrument, I have come across Concertina Connection. The Jackie looks like my favorite, so far. Are there any other choices that would fit my criteria better?
-Daniel