I think the price at a LFS isn't too bad unless you have a monster sized tank that runs through this stuff daily. I'm only around 40 gals... go a 1lb supply of Kalkwasser will last me for quite a while. I only use it as top off... so far everything looks great, lots of coraline algae forming.
Gary, talk to that one guy at Fishes of Eden... he has told me A LOT of stuff and anything he says I follow.