Usually the mark up on some of these boats is massive, you can certainly negotiate a deal for yourself, even if they're unwilling to move on the price you can negotiate for things like, registration, safety gear, anchors etc. i've done it plenty of times in the past.
Another trick is to spend an hour with the salesman asking every question under the sun, then tell him you'll take it now for cash if he knocks $1000 off the asking price, if he says no, tell him you'll think about it and start walking away. after the amount of time he has spent on you he'll almost always call you back and say $750.