I'd haggle EVERYTHING and ANYTHING.
First the price of the bike you want, then the p/ex for your SV. You'll end up haggling over the cost to change. When your close to a deal, ask them for any extra's, heated grips? New tyres? whatever takes your fancy to secure the deal. Make sure it's freshly serviced, and CHECK the oil to make sure it's nice and fresh (golden brown or black sludge?). If you have to finance the difference, make sure you get finance in place before you even set foot in the place, unless they're offering 0%, but highly unlikely on a used bike. Don't let the b**gers get away without taxing it before you pick it up. Stick it too them (but don't quite get thrown out of the shop) If all this works, find somewhere else to get it serviced, they'll never forget you! Good luck