I voted 5-10k. I figured 100 rounds per week, 52 weeks a year. I don't shoot every week, so on second thought that was probably a bit high.
You asked about pistols, but I probably shoot the most out of my .44 Magnum Ruger Redhawk. It is a big 7.5" model with a 2.5X scope. I reload, so it is not expensive or punishing to shoot, but is a real tack-driver.
Aside from that, probably .45 ACP, out of my Para GI Expert 1911. I've always liked the caliber. I shoot 9mm slightly better (more accurately and quickly) but it is just not as much fun. To me, it is so easy to shoot a 9mm well that I feel like I'm cheating. Not enough of a challenge, I guess.
Very close to the .45 ACP is .380 ACP. My Bersa 383 (predecessor of the Thunder 380) is just an awesome gun. Very accurate and easy to shoot well. Ammo cost is not much of a factor any more, since I can reload it for around $7 a box instead of getting raped for $20+.
Things may change this year, since I just yesterday got laser grips for my SP-101. Between the accuracy advantage that will give and not having to chase brass, I will probably shoot more .38 Special-level .357s out of it than I will .45 ACP this year.
All you guys who would like to shoot more but don't, should really get into reloading. In my experience, you won't save any money, but it will be because you are shooting twice as much.
$200 is plenty to get you going with a nice single stage set-up. Plan on 100 rounds an hour, and it is pretty fun to do. I feel like a mad scientist when I'm reloading.