Do you have lots of gallon cans of unused paint in your basement? Did you know that you can mix brands of paint? Did you know that you can mix gloss, satin finish and flat paints, too? As long as you do not mix latex with oil base there are no rules! Mixed finishes will take on the duller or softer of the mix. Hey. It’s only paint! What have you to lose? The next time you want to spruce up a room in your home with a new coat of paint, try mixing a few of those unused cans of paint in a large plastic pail. Save a little paint from each can for touch-ups if the paint is still current in any room. Figure out the square footage you need to cover and mix a little more paint than you think you will need. 
I have found that I only buy colors I like, right? Often, those colors blend very nicely with one another, and, if you add a bit of ceiling paint to it, you can lighten any dark color very easily. Experiment first with the colors in an old foil pie plate. Think about it. You can save money and avoid the unnecessary dumping of paint in your local landfill.