Spend some time, look at a lot of boats, everone else does when they are going to buy a boat it seems. One thing though, if you find the "perfect boat" walk a way from it and think about it for a day or so.
Take a look at ebay (never buy here unless you actually inspect the boat), save likely boats in My Ebay and see what they sell for. I think of these as real prices of what sailboats are worth now days. I was surprised on how cheap sailboats are.