When you need a small amount of paint for touch-up check the craft department. Walmart has every color and they cost about $1. I've used it on furniture, artwork, walls, cabinets, floors, and much more. If necessary you can buy two colors and mix them on a styrofoam plate. You don't even need a brush, use q-tips or tooth picks. I got the copper and painted the hinges on my cabinets when I changed hardware. That was over a year ago and they still look great.
I do tole painting and therefore have several "jars" of acrylic paints on hand. There are other uses for these paints: touch-ups on walls, furniture, small spots on clothing, appliances, tiny scratches on cars, toys, etc.
Quick Paint Touch Ups