Bump to this thread. I was considering making a Gluten Free beer for a friend. My LHBS doesn't carry Sorgum because that cannot sell it they say. I hear it doesn't taste that great anyway. I would just use the ClarityFirm and be done with it but I really would love to get as close to gluten free without it.
So that would leave the following grains.
Amaranth : I cannot find Amaranth malted
Oats : Which you can get malted
Buckwheat : Can be had malted as well.
Millet : Millet malt
Rice : https://www.glutenfreehomebrewing.org/STOREProduct/953/Crystal-Rice-Malt--5-LB.html
Corn : https://www.glutenfreehomebrewing.org/STOREProduct/976/Organic-Corn-Malt--5-LB.html
Quinoa : which I cannot find malted but I can find flaked
So besides Honey, Maltodextrin, Sorghum and straight up sugars I wonder what else might be Beerable™ in a beer