Wecome to the dark side, Chris! Come on in. We have cookies.
Seriously, though, shooting is a whole lotta fun, and you can get lots of good information here. As aarondgraham pointed out, a good .22 pistol will get you tons of trigger time, without huge ammo expenditures. That said, you'l need to figure out: (a) what's the purpose of the gun (target, self-defense, both?); and (b) what do you want to spend on the gun. Ammunition costs will also need to be considered in choosing. There are tons of "what gun should I get" threads up in Hogan's alley; you might consider browsing some of those to get a heads-up on some of the options available to you, and some of the reasons for choosing one pistol or another.
Edited to add: Oh, and you might as well learn the Four Rules now. They are of critical importance.