So it seems the fan in my mid-2009 15" MBP is dying.  I bought a screwdriver on Saturday (actually a set, but whatever) to open up the bottom case as I didn't have the right size already.  Just hearing it, I thought it was a dust problem, so I cleaned it out (needed to happen anyway as it's been almost 3 years without an internal cleaning).  Found a loose screw which was part the left fan array, and I thought that it might be responsible for the noise.  
Closed it all up and it seemed to be fine.  But then I get this horrible grinding noise again from the left fan.  It doesn't happen all the time, but it's definitely not good.  So I need to replace it.  Right fan could probably use a replacement as well just to run quieter, but it doesn't have the same issue and I'm a bit strapped for cash here.
Now prices on a replacement kit for this fan vary anywhere from $8 to $60.  The cheaper ones are on Amazon.  I need to open up my computer again and check the manufacturer/exact model number though before I'd order one.  
Anyone else have experience with this?  
Hopefully the ones in the $8-$20 range will be acceptable.  I think the other vendors are probably just markups.  I may need to buy that special star-shaped screwdriver as well - we have a couple of those laying around, but I'm not sure if any are the right size.  May also grab one of those prying tools for a couple bucks since I'll need to separate the fan connector to the circuit board.