Fandain,
The answer to that would be a yes, and a no. No, you can get any channel you want to buy. Yes, you don't want to be on the same channels as a lot of other pilots at your flying field. The best thing to do is contact your club and see if they maintain a list of members and what channels they are on. If so then buy a radio on channel with little or no use. The club can be important too because some fields have channels that have interference on them, so you don't want to buy that channel. If they don't maintain a list just make trip to the field and watch the frequency board and make notes on what channels aren't used much. This is important because you don't want to have to sit and wait for your channel to clear before you can fly.

Hope this helps

Ken