In my experience, about 3/4 of the cost of a renovation, repair or upgrade is labour.

If you are prepared to get your hands dirty, learn some new skills, and have the desire to do a good job, then do the work yourself and save some pretty decent coin.

If the only reason for doing the work yourself is to save money, take some advice from the Home Depot 1-2-3 books and hire a professional.  It will cost you less in the long run because you won't be paying someone extra to fix up a crappy job.