As you may know, Home Depot is abandoning Marth Stewart paints. At my local store, they were dumping 8oz bottles of sample MS paints for fifty cents. Assuming 1 gallon normally covers 300 sq ft, an 8oz bottle should be good for something less than 19 sq ft.
I picked up a few bottles for a current project - a six-foot valence. Seemed more economical than buying a quart.
The store was also specialing Behr samples, but the amount (like 1 oz) was more suitable for doing fingernails.