You'll still need to take the whole unit out, but you could save by buying just the fan.
If money is no object, by all means get the whole unit. OEM is not cheap though!
Just discovered I have you a wrong link, just the fan: http://www.ebay.com/itm/NEW-IBM-Thinkpa ... 0838231479
Price ca. $12.- (check the part number resp. the fan model/name on your current cooler).
Thanks again, RBS. I'll think about it. Though I'm tempted, because the fan in the ad is so cheap, I just like how the OEM fan I got (the second fan IBM sent me -- the first one it sent me was defective, probably used) came with the exact required amount of thermal paste already applied to it. The reason I say the first one IBM sent me was used or a refurb is because it didn't work and it didn't come with the thermal paste. Applying the thermal paste properly is something I would do wrong.