Piece of piss. Dare I say it the cans from Halfords are quite good in my experience. Should be about £12-15 for the primer and paint - you'll have lots left so you could do your door handles too if that's your kinda thing.
Looking at the pic your bumpers appear to not be colour-coded as well (as they should be on an SE) and I'm pretty sure that they were dechromed as well - are you sure it's an SE?
