They're just a place that has lots of stuff ranging from starter plants in 3 inch pots to specimens purchased across the country. According to Michael the owner, he buys some from estate autions, some from growers. From year to year, you never know for sure what he'll have because it depends on what he finds on his buying trips. This year he had a bunch of Bald Cypress he picked up in Florida. Most of the plants mentioned in this newsgroup are there.
Prices range from a few dollars to over a thousand for some of the older specimens and groves.
They have regular classes. Some are free. Most are very good value. You create one large bonsai and two miniatures. Materials are provided.