You can use cheap primer (bad, since it will be porous and will have to be removed for a good layer of paint), Blitz Black or other cheap implement paint (doesn't hold up well, also should be removed), up through decent auto paint with flattener added, to speciality paints.
Best to discuss it with your paint supplier and get the best product you can afford.

Can it be scuffed and shot over?
Can it be cleaned?
Can it be touched up?
How long are you planning on keeping it?
Indoor or outdoor storage?