grow medium, other plants, agar

[BearyFaery]

I'm about to order some seedlings to begin my growing orchids project (flowhood complete!), and I figured seedlings are a good place to start and then work backwards until I grow from seed.

A few questions we came up with.

We want to one day attempt to make our own grow medium, a question my fiance brought up, however, is whether or not any other plants grow well in the medium. Perhaps at a less expensive litmus test to see if our medium works or not.

Also, anyone have any tips on inexpensive places to get agar? We have a health foods store in the city that sells it at ridiculous prices, just trying to shop around.

Thanks in advance!