I want to use stones for a shrub bed. Where do I get them, and what is the approx. cost?

I am leaning toward natural mixed rocks for the bed. . .pebble size. Basically I want these to take the place of the wood chips surrounding the shrubs in the front of the house. I know you can get these by the bag at a garden store, but I'm looking at a 600 sq foot area and decent coverage (covers the underlying weed "plastic"). Are there companies that deliver this by the truck? Any rough idea of the cost for such a project?