Yes, you can use acrylic paint instead of citadel paint, but you have to compromise the quality. Heavy-body artists' grade acrylics are the best alternatives to citadel paints. Although you might get a different range and finish than citadel paint, good-quality acrylics can do a decent job and save you some bucks. P3, Vallejo, Kimera, Pro Acryl, etc., are the best alternatives to citadel paint for small-scale miniatures.