How much (ballpark) should one expect tomget off a second hand E70?

[Spanky Deluxe]

We're looking at buying a second hand E70 at the moment and because of the relative high cost of these, we're looking at buying from a dealer (BMW or independent). I'm not a fan of haggling so I was planning on going in and saying 'this is how much I'll be willing to pay and here's my number, call me if you want to sell it at this price' since I've heard that's a decent way to get things done.

Can anyone suggest what kind of % I should aim for? We're in the UK but I'm guessing this kind of thing transfers over the pond in percentage terms at least. I've seen a couple of E70s (2008ish diesel 3.0 se or sport) listed that have the options I want but they're about 10% more than what we'd like to pay. We'll be trading in our late '04 X3 3.0i Sport. I can sell privately if need be but one dealer's already said they'd give me about what I'd expect to be able to get for it privately anyway and the hassle of getting short term insurance etc and arranging viewings would likely not be worth it.

I know dealers are more likely to give money off if taking up financing but we'll be paying cash.