Genuine are around $110 - $180 and in my opinion are too small. If you can find a Borg Warner one, which is similar to the genuine one but bigger you are laughing. I think they cost a bit more but are worth it! If you do plan to get an after market one, I suggest that you get one that is radiator style and not cooling fin! (cooling fins are just were they get a pipe and bend it while putting fins through it).
Hope this helps buddy
"Give me any task to do, and I will find something else to do in it's place." Plato - a definition of procrastination