First, pull the serpentine belt off and make sure the sound goes away. Then, if it does, spin all the pulleys by hand to be sure that it is the A/C compressor that is making the noise. There can be more than one bad pulley, so spin them all just to be sure. Give them a good wiggle too, sometimes a pulley will get loose even before it gets noisy.
I think that most of the A/C compressors on e-bay are used or cheaply "remanufactured". One of my friends bought one and I installed it for him, so far (only 4 months) it's good. You don't have to be certified to work on an A/C system. The sticker under the hood that says "this system to be serviced by qualified personnel only" or whatever is just for the manufacturers liability. You need to take it to a shop and have the refrigerant sucked out, and take it back to have it recharged, but you can do everything in between yourself.
There are many A/C bypass pulleys that bolt on in place of the A/C compressor to maintain the factory belt and routing. Some engines don't need one, you can just go with a shorter belt. I believe you can do this on the 2.2, but I'm not sure. Check your routing before you try this, many times the shorter rerouted belt will rub on something.