My wife and I just painted the interior of our house with about 6-8 gallons, of $30+ per gallon (meaning the good stuff, non-diluted) with absolutely fantastic results. However we just paid an average of $5 per gallon. Reason...all big box stores have paint, set aside, that has been mixed but not picked up by the customer. They need to sell it quick and if you're not in a hurry (you know well in advance that a room or two need painting and it's not like the roof leaking and needs an immediate fix) you can go to each store when you need other supplies or food, like Walmart (when convenient, driving 20 miles to each is not worth it) and over the course of a month or two, pick out some very nice colors of quality paint. We found perfect colors...not saying they were our first choice but when we opened the can, very nice and some even better than our original picks. Cost to paint the entire house was about $100, with all materials included, period. We had it on the market for a few months to sell, didn't sell, painted the rooms, got 2 offers the day after we finished, took the best one and never looked back.