You can buy stuff off ebay, about £7/tin delivered. Its for calipers etc. Horrible to spray with - dusty. Can get a load of different coulours.
Be aware, they only go tough after theyve been heated. Before then they scratch very easily.
Ive also got a tin of whatever woodwarm stoves use. I cant recall the cost and i have not used it yet, but that may be nicer to use. Kind of a metalic black.
I noticed my local car spares shop keeps rattle cans of high temp 650C paint intended for exhaust manifolds etc. at around £6-50 a 440ml can. All in quite a few colours too.