[sigtau]

I believe you can get replacement components, gearboxes in particular. OR many people just get spring pistols, which often are cheaper and have a pretty decent velocity to them as well. Springs aren't bad as sidearms.

If you guys happen to know of a spring-based revolver that doesn't rattle like hell (thereby killing all chances of stealth), please do tell.

[Thaeris]

I have a spring slide-action pistol, modeled after a 10mm auto. Purchased from Wal-Mart for less than $30 USD, mind you. I'll look more into the specific make and model later if this is of any interest.

[esarai]

Ooh I had one, it's a replica of the Walther P99, springer, mostly plastic, 13 shot clip.  Forgot the manufacturer, will update when I'm next near that thing.  The clip has a large metal chunk in it, making it heavy and a very steady weapon.  Decent velocity and good range.  It clicks a bit when you cock it, but no rattling, so you can easily maintain stealth until you're ready to fire.