The site for "Tissue Culture in the Home Kitchen http://www.omnisterra.com/botany/cp/slides/tc/tc.htm" posted by Scott
mentions Sigma Chemical as a source, but includes this bit, "They tend to be
a bit uptight at this company, so you may need to get a "fee-exempt" nursery
license from your local Agriculture Department before SIGMA will do business
with you"
Since Sigma can be difficult to order from as an individual home
experimenter, anyone wanting to try their hand at home TC should check out
Phytotechnology Laboratories at http://www.phytotechlab.com/. They seem to
have no restrictions on who they sell to and the prices are very good. I
have ordered from them several times.