Brake Caliper

Need a new rear brake caliper, can they be rebuilt? And is it worth rebuilding it?

What year?
Check Rockauto.com it will give you the prices for calipers and repair kits. For the front caliper on my 94 it's $15 for a new(rebuilt) caliper and $7 for a kit. Why bother.
94

You can typically get fully loaded calipers for around 50 bux. Include rebuilt caliper, caliper frame, new slide pins, and pads