It can be done, it's not hard actually. You may need to be able to use a soldering iron and multimeter. But it really will cost more than a new one. Best bet is for you to get another similar model & put your current hard drive in an external case to use as a backup device.
If you really want to look into repairing it, start at
http://www.ifixit.com/Guide It's mostly Mac but there is some PC stuff and the principles are the same.