I'm not sure from your post if you plan on fixing it yourself or if you want to know what to expect from an a/c shop.
First thing you have to do is figure out why the a/c broke down. If you're sure you need a compressor and dryer, you can do it yourself. But you need compressed air (to flush out the system), vaccum pump (to evacuate air before charging), and manifold gauges for proper charging pressures.
It's easy to fix an a/c so you get cold air (as in your case).....but much harder to fix it PROPERLY so you get cold air for a long time.
For parts, try ackits.com or caawparts.com. Both are reputable a/c experts and trustworthy internet dealers. For more expert advice on a/c, go to aircondition.com to talk to specialists.
95 E320 Cabriolet, 131K