Most beauty supply stores have them. If you live in the Los Angeles area, you can find them at Han's Beauty Supply. I just picked some up last week. Otherwise, any beauty supply store should do.
Go to the cosmetic/shampoo section of your local Wally World and you should find sprayers from 4 oz. all the up to 16 oz. All very inexpensive. The small pump type 4 oz jobs really put out a fine mist.
I was at Wally World the other day and found the bottles Natty is talking about. They have a nice selection. You can even pick up a few travel containers for some of your favorite liquid wax, glazes, etc for the road. I thihnk I bought a four pack of 3 oz (??) bottles with flip tops for $1.50.