Out of the 'profit' you have to take out overheads as well, which you seem to have forgotten. In reality, most discount operations rely heavily on you taking out finance and retro's from the manufacturer.
If you buy a bike, and finance it , the dealer has a minimum cost of money lent by the finance company, say 5%. If he sells you finance at 8%, he pockets the difference, if you buy at 10% he earns even more. And he gets a signing up fee, too. If you buy protected finance , in case of illness etc, he gets a bung, as he also does if you take out shortfall insurance( well worth having on a desirable bike, BTW).
At the end of the year he receives a payment for units sold/registered, hence so many pre-reg bikes on sale. This is a BIG part of their planning, financially.
A typical jap dealer makes very little out of a new bike, the money comes from retro discounts, finance, servicing, warranty work( for which they're paid a reduced workshop rate), and accessories. It is far more profitable to sell S/H bikes. BMW dealers should make a little more, but it's much the same for them too.
So, when you try and chip your dealer, and he says 'I'm only making £200 on a £7K bike, he's sort of telling the truth, and if you give it the big 'I'll pay cash', that's the worst news he's heard all day! Dealers are there to make money too, and, if they're screwed too often, they go bust. Motorcycle City, anyone?