Well its just like anything else. The prices on the website are the RRP. A 150XL Optimax retails at £10245 but You can buy one from a Mercury dealer for a lot less than that!! The same thing applies to Tornado/Viking/XS and probably a lot of others too.
Just ask for a quote and specify everything you need. You'll get two prices off Barnet, the total RRP of the package and their most competitive discounted price.
All I'm saying is the prices on the site are only a guide really and the boat will cost less than simply adding up all the extras on top of the package price.
By the way if you really want to make a killing, try and buy at a boatshow, mine would have cost 3-4k more had I not. Barnet will be at the Southampton Boat Show in September or London in December.
If In Doubt, Go Flat Out!!