No offence intended to Biker Biggles, but I think £500 is on the harsh side.
May be worth taking the lowers off the bike too if they're a bit tatty as will detract from the overall appearance.
A couple of hours spent with some Autosol and elbow grease can get the fork lowers looking presentable. If the exhaust down pipes are grubby do them too.
Little things like that may only be cosmetic, but can add a couple of hundred quid in value.
Just my two cents worth
