I've got two prostaff's and they are reasonably clear and hold their zero well once I got them zero'd. The two that I have don't seem to track consistently, but again, once I got them were I wanted, they seem to stay. These guns ride everywhere in the rifle rack on my 4-wheeler and do a ton of bouncing around, so if they were going to move around, they would have done so. That said, they are as cheap as I'd go.
Another scope that I've had good luck with and is very durable in that price range or close to it, is the Burris fullfield II.
I've tried a variety of simmons', tasco's and a vortx crossfire and can tell you from experience, that it is alot cheaper to pay just a bit more on the front end. These brands just wouldn't hold up to any abuse in terms of holding zero.
