Just tagging along.
Here is my two cents. Kalkreactor is definitely cheaper than Calcium reactor. You can buy a very nice setup of Kalkreactor for 65 dollars without pump from this guy at reefcentral. Hes from washington but not a member of this board or club.
Anyway, Calcium reactor is more efficient I guess in delivering calcium. In Kalkreactor, you are just relying on your water evaporation while in calcium reactor you can add a more concentration. So if you have high demandind corals then calcium reactor is your choice.
Remember that in Kalkreactor, you can only saturate the freshwater with kalkwasser to such a point and thats it. I think its two teaspoon per gallon.
Right now I am using a 10 gallon glass tank to mix my kalkwasser. Mix it for several hours. Then settle, then I have a 10 day supply of calcium/alkalinity for my tank.