They carry an astounding variety of Acers, some extremely rare. Ken's Bonsai Gardens 471 Page Mill Rd. I was very humbled by visiting his gardens which are located in his small front yard. This is a very good way to begin a new bonsai. Friendly and knowledgeable service.
Prices are reasonable.
Also have many nursery grown varieties. Write for a catalog. Bonsai Nursery 3750 S. Federal Blvd. One 20x75 foot roundtop full of bonsai. Also nice outdoor display.