What's the average cost of a patch repair on a car?

I've got an '89 Jeep Cherokee with 3 or rust areas ranging from tiny golfball sized to 4"x6" holes that have rusted through. The superficial ones I feel I can sand, fill and prime myself. However I'm not really knowledgeable enough to fill in some of the holes, and am I thinking I should have a body shop prep those before paint. What kind of prices am I going to be looking at? Does anyone kow what a typical small patch repair ranges from? Thanks for your input.