That's a handy link, thanks.Speaking as someone who has done things the cheap way and the expensive way.
Go with the ULTRACAL for sure. Way nicer product. The molds stand up to a hammer strike. I know becuase i have destroyed my fair share of older molds.
Here is a link to a state by state link to distributors of whatever type of gypsum cement you need.
You can find a local place via this list and save alot and buy a large quantity!!!! And support local buisness at the same time.