bctbct is right... a crash can be expensive, and I've been there and done that. I bought an R/C plane back in 1999, and I had it wrapped around a tree within seconds of take-off. I was so pissed that I gave it all up right then and there.
Fast-forward to 2006. I've spent a year in competitive R/C car racing (RC10B4, BJ4) and it was a BLAST. The problem is that it took up so much time and money (to be competitive, you have to constantly perform maintenance and keep up with the "equipment wars").
I didn't want to give up R/C, but at the same time, I didn't want to have so much time and money invested in it. So now I fly an Align T-Rex helicopter. It's a BLAST. I don't need to constantly buy new equipment, there's very little maintenance, and most crashes aren't that bad (< $20).
The trick is to practice on a simulation. There's one sim called Reflex XTR. It's about as real as it gets. I cut my teeth on that before I took my bird up. It's a $200 piece of software, but if you figure how many crashes it saves you, it's a great investment. On top of that, it's photo-realistic. It's a blast.
I would definitely start with helis over planes. A heli is easier to land and MUCH easier to keep close to you. A plane gets away from you REAL fast. A heli can, too, but you can lift off the ground in a very controlled manner and keep it in a small area. With a plane, you have to take off and that fscker is GONE before you blink.
