Craftbrewer. Emailed that cheese shop that got mentioned and they only had it as liquid and didn't know the concentration, all the other websites were listed as selling as 25kg bags only.
What's the tap water like in your hood mate? 'Tis extremely soft here so it's acid rest or Ca additions for me. And Ca is easier :-P
Hmmmm, I assume my water is similar to yours, and I'm planning a Bohemian Pilsner for some time over Easter. Sounds like I should figure out how to work Mr Palmer's spreadsheet!