It will cost three times as much as you think it will and take twice as long. I guarantee it.
It can be a lot of fun, though. Set aside the cost of the work, for a moment, and ask if you really want to get into the project. It can be very rewarding, but it takes a tremendous amount of time and there are occasions when you'll truly wonder why you ever got into it. Which is why you have to want to do it for the sake of improving the boat to your own standards.
In my experience, it is almost always more cost effective to buy a boat that has already had the major work done. That's just a reality - you can burn through a $1000 in no time at all. I purchased my boat in May 2007 and I've already got more than $15,000 in her - above the purchase price and I did not start off with a project boat.
It depends totally on the scope of the project, the type of sailing you intend to do, the size of the boat, and the standard to which you want to do the work.
You will probably find Tim Lackey's encyclopedic website very helpful: http://www.triton381.com/
Here's a link to where he goes over the numbers (click at your own risk): http://www.triton381.com/projects/re...ion/budget.htm
. Bear in mind that he is a true craftsman, so while he gets "free" expert labor, his boat is completed to the very highest standard.