Franz Heymann wrote:

Where does one buy Agar?
What does it cost?

See previous post for the answer to both the above.
What is wrong with simply making up a weak jelly with ordinary "food" jelly?

Try it.. you asked what was used, not what you could try to use;-) I
suspect you may get other contaminations though. We were told to avoid
anything that grew a pink slime.. NOT in humour I think it was sign of a
culture of a human contaminant.. Its all to easy to breathe on gels
whilst preparing (esp in a domestic setting) and grow something you
don't want to !
//
Jim