Paint gets more expensive as you go from flat to gloss. The difference is usually around $1 per gallon per sheen upgrade. Flat is the cheapest, then matte flat or eggshell, satin, semigloss then gloss. Paint also gets much more expensive the darker it gets. A white or neutral paint color can be as much as $20 less expensive than a deep base red or blue.
If you paint over dirty, oily surfaces, the paint will easily chip or peel off. So before painting, clean grimy areas with a deglosser or heavy-duty cleaner intended for prepaint cleaning. They work well to clean painted, varnished or enameled surfaces to improve the adhesion of the new paint. They’re ideal for cleaning greasy or oily areas like kitchen and bathroom walls and removing hand marks around light switches and doorknobs.