If you don't want to talk, then you can go to RadioShak and get a decent scanner that will let you listen to aviation freq's for about $40 bucks. It'll require a 9v battery and allow you to preset the freqs you want to listen to.
If you insist on a transciever, I've got an ICOM ICA4 that I bought from a radio distributor called BearCom. Their website is something like bearcom.com, but be prepared to shell out a few hundred bucks. Even the cheapest transcievers from Sportys are going to run you $250-$300.
When I bought my Icom, I had a job that justified being able to contact the control tower on ground freq's, was flying GA a lot with a friend who owned an airplane with a radio that had issues.
While nobody's ever said anything about my transciever, I check it if I'm going to take it with me on a commercial flight because I have no earthly idea how the TSA is going to react to a transciever, or even a simple scanner.
As they don't transmit, I can definitively say that you need about as much licensing to purchase a scanner as you do a television. Whether or not I should have a license for my transciever is a point of greater debate, and not part of your question. (What are they gonna do? Order me to sell it?)
So, you can probably pick up a cheap, battery operated portable scanner at RadioShak, Fry's or BestBuy for around $40. You'll also be able to buy AC and 12volt DC powersupplies so that you don't have to continually buy or charge batteries.
Happy Scanning