Rear Window - '98 4Runner

[snowripper]

My rear window has started acting up and i need some advice. if i try to
roll it down, it sort of jumps down a few inches at a time. Sometimes it
only does that the until about halfway down, then it rolls down fine the
rest of the way. Sometimes it will jump down, then if I release the switch, it will automatically roll back up until closed. I have tried using both the switch up front and the key in the rear door, both reproduce the problem. So is this likely a switch problem or motor or both?? If both, how much am I looking at to replace? Can it be done without spending hundreds at the dealer? Can't live without it, nor can the dog!

Thanks in advance!
-Tim