Good a/c compressor source?

[recian]

So today I was under the hood doing brake master cylinder work to my truck. I noticed the compressor is covered in oil/dye. Now I know why my a/c has been getting weaker. Has anyone had good luck with the common Four seasons ones they sell at the local auto stores and rockauto? Or is there any kits to rebuild them? I'm a bit low on funds thanks to my brakes and eastern NC in july/august isn't the time of year to not have a/c.