I agree with Mike, most Sportsters are about the same. I'd be more concerned about the mileage, upkeep, condition and the like. It's a 13 year old bike. Unless it is extremely low mileage, garage kept and in extremely good condition, I wouldn't pay over $2-3000 for it. Just my opinion, though.
Painterbabe1: Take all the usual precautions in examining the engine and transmission, BUT also check for corrosion around the battery compartment, rust inside the fuel tank, fork and shock seals leaks and tire age/condition. Suggestion: Get the seller to split the expense with you of taking the bike to a H-D Dealer and have a total service run on it including changing ALL the fluids. Most certainly unless the bike has had topnotch servicing, the fork fluid is contaminated. ................... BC