You can put the new timing belt on, then perform a compression test. If you find 0 pounds in any cylinder, it's time for new valves. As for cost, there's way too many variables. Get a couple of estimates from some local shops. You most likely won't save any money by removing the head yourself unless you already own all of the special tools needed. As a ballpark guess, I'd expect it to run at least $2500.00.
If you buy the needed tools to remove and replace the head yourself, take the head to an engine machine shop to have it checked for cracks and surface flatness. They will be able to replace the valves and touch up the seats. You'll still need an air tool to clean the block surface and produce the proper surface finish for the new head gasket to bite into.
Loosen the head bolts evenly a little at a time to prevent it from becoming warped. Be sure to torque the bolts according to the procedure in the manufacturer's service manual. With aluminum heads that usually requires the use of a torque angle gauge, or at a minimum, a click-type torque wrench.
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Wednesday, January 25th, 2012 AT 4:26 PM