Laughingdog, I like to paint inside and outsiide my coops for easier clean up. When I buy the paint I choose lighter colors in an attempt to keep it cooler.
Although I did try to match my house once (wrong color but a nice tan anyway) I usually look at the returned paint shelf. Lowes calls it Oops Paint. A nice exterior paint that goes for $20 can be as low as $8. The deals usually aren't so great on quarts so I stick with gallons. Make sure it is EXterior paint or it will wear off quickly. When we get the big coop ready to paint, I will use interior paint on the inside.
I also figure bright, light colors make it easier for me to see bugs! I purchased two dog houses to use as coops and they need a good coating of fresh paint inside. Then the chickens can poop everywhere and it might wash down easier, lol.