They are a national paper that specializes in classified ads for used camera equipment. Also, try the used equipment classified ads in the Photo Shopper. For new high end equipment a good source is 3-D Concepts . They specialize in RBT products. Check the Links page for other sources.
Standard film is used.
The best available mounts in terms of precision and accuracy are the Albion aluminum stereo mounts and RBT plastic stereo mounts. The best mounts in terms of economy and value are the Cardboard Heat Seal mounts. There is no simple answer. All of the most popular models are of good quality, so the key is the features and layout that you prefer. The Busch Verascope F40 and Belplasca are also excellent, but take a non-standard format which you must always mount yourself.