Rear End Squeak/Chirp - Bad Shock?

I have an annoying squeak type noise that I notice most when pulling into my indoor parking garage at work. As I'm slowly heading up the ramps I hear a squeaky/chirpy sound as I go over little bumps or accelerate/decelerate. I initially thought it was the emergency brake cables where they route through the metal guides so I lubricated them to no avail. I put it up on the rack last night and while inspecting I noticed oil dripping from the bottom of the passenger's shock. The attached pics show the oil after I had already touched it with my finger, so there's not as much. Also, the entire shock was coated in oil. So, I'm thinking this is the culprit. Has anyone else experienced this and for those who've changed out the shocks, where's the best place to purchase, am I ok just replacing the one, and is it a pain in the ass to remove and replace it? Any comments are greatly appreciated.