Used fans work great!
My brother's Macbook Pro was making some interesting sounds on top of overheating. We did some research and came across ifixit.com how-to articles. From there, I ordered the fans (used), and the problem was fixed!
Removing and replacing the right and left fans (Macbook Pro 15 mid-2009 2.8 GHz model) was simple. I ordered the required tools (Philips #00 screwdriver, spudger, & anti-static wristband) along with the fans, unscrewed the bottom plate, popped out the connectors with spudger, unscrewed fans, and then did the reverse. Simple!
2 pieces of advice: use an anti-static wristband and be careful while handling the spudger to disconnect fans.
MacBook Pro 15" (Late 2008-Mid 2012 excluding Mid 2009 2.53 GHz) Left Fan
MacBook Pro 15" (Late 2008-Mid 2012 excluding Mid 2009 2.53 GHz) Right Fan