I am selling the factory 4 pot calipers off of my 06' WRX. The passenger side has 1 stuck piston, and I don't have the time or tools to rebuild them so I took the lazy way out and bought new ones. The red paint is in rough shape from normal seasonal use, but there are plenty of DIY tutorials on how to rebuild them. If it helps I found good prices on all of the replacement parts through SubaruGenuineParts.com. I'm asking $250.00 OR BEST OFFER shipped (continental USA only) based on other sets I found for sale on other websites.
Here is a link (a different website, I know), to one of many 4 pot DIY rebuild tutorials for those interested.
Subaru 4 pot Rebuild w/pics - NASIOC
Thanks for looking!