Just to chime in on Glycin, I just ordered via telephone from Photographer's Formulary today a Pound of Glycin which cost 80 USD. Compared to Hydroquinone that is a lot of money. But if you figure you use a liter of working solution and you only use 5 grams of Glycin that means it costs something around a dollar a batch for the Glycin which isn't enough to worry about too much but then the issue is definitely storage if you want to keep it bright and fresh. However I just tried it out last week with Glycin that was stored room temp in a drawer for something like 2.5 years and it was a light brown color but worked fine.

PS Also right now at Photographers Formulary they have free shipping for a pound of Glycin.