My buddy bought the $500 "Outdoors Do-All thrower" from Cabella's. The first one worked fine for a few hours, and then promptly began shattering every pigeon we attempted to throw. He had to deal with the manufacturer on this, as they are shipped directly from them. The service was excellent, and they sent him a brand new unit even before he returned the old one. When he got the new one, same problem. After many hours of tweaking and diappointment, we discovered the throwing arm needed to be bent to a precise angle to work properly. It's worked almost flawlessly for thousands of pigeons. I'd stick as close to the $1000 range as possible to avoid aggrevation. Cabella's sells the Atlas thrower for $800, and while I haven't tried it, it looks a lot better designed in the launch pad area than the Do-All. Hopefully someone will reply with better info on throwers they have, I just wanted to alert you to problems with the lower end 12V units.
p.s. If you decide you want to try the Do-All or something similar and tweak it yourself, I think the last time I checked Cheaper Than Dirt, they had them for $400.