Hey,
Are we talking about a cheap boat, medium boat, or expensive boat? Common type of boat or rare type of boat? The rules are different for each type. If you are looking at buying a cheap, 30 year old boat, just to play around on the water, there are thousands available and you can get a great deal. If you are looking for something specific, expensive, relatively rare, that market is completely different. For example, if you decide you want a J111 for one design racing. You are not going to buy one for %50 of asking price (assuming the asking price is reasonable). The reason is that the market is well known, the number of boats available is small, and that's the way it is.
When I was in the market for a boat (in 2006 and again in 2013) I did a lot of looking on yacht world, other internet places, and local marina's. I decided on the particular model boat I wanted (3 types in 2006, 3 again in 2013) and then I decided on the highest price *I* could afford (which was way lower than what most models were advertised for). When I found a particular boat that looked good I would call the broker to get a feel for the boat. If that checked out I would go and look at the boat. If that checked out I would call and tell the broker my sad tale "I love the boat but I only have $XX. I know it's way under your asking price but it's all I have." In 2006 the offer was countered, I was able to come up with a few more $ and the boat was mine (after survey, etc.). In 2013 my offer was rejected. The broker received and accepted a higher offer and I thought that was the end of it. Two weeks later the broker called me back b/c the first deal did not go through - buyer could not get financing). I had to come up with another $500 and then we did the deal.
I always buy boats in late fall - that saves the current owner the cost of haul / store - which gets passed on to me. Of course I then have to cover that cost ,but it gives me the winter to really look the boat over, clean ,decide on course of action, etc.
Lastly - to those of you who state that there are SO many boats out there to buy - just wait until you actually try to buy one. Yes ,there are lots and lots of boats out there - but many are overpriced junk and not worth the trip to look at.
Good luck,
Barry