Do you havea decent selection of tools? Do you want to wrench on your car? For the price of someone installing headers, you may be able to pick up a decent set of tools...Christmas is coming as well, lots of sales at Sears righ now...
Off the top of my head...normal wrenches, sockets, universals and extensions will get em off. It's all personal technique how you use the aforementioned combinations to get to the bolts...don't be afraid to remove other components to get at a bolt. Defeinently do-able, even for a beginner. Pass side is easy, after removing the smog stuff and inlet ducting, driver side is a bit more challenging, I've always gotten mad at the forward bolt, PITA with the power steering pump right there.
A jack and stands, unless you have other means (lift or something) is helpful when trying to get at the joint between the headers and H-pipe
All-in-all, do it yourself!
Good luck