There are several acids that would work. Many available locally as well as artcraft or the Formulary.
Sodium carbonate is the real killer. Many of the "Art" papers are buffered. It also seems that the more buffering they put in the paper, the more they charge. So it could be cheap paper for Cyanotypes is the way to go.
I use Arches and Fabriano. We can search the archives of the alt list and find a number of papers to try.
Locally (to Salt Lake) we can find papers at Reuels Art and Frame. I buy from Daniel Smith and Dick Blick.
If we start with the right paper, we can save ourselves much pain and suffering. I don't worry about the water too much, I soften and filter it, my ph is about 7.4 in West Jordan. I'm sure it will change once the new house is done in Lehi.
Cyanotypes can be done on fabrics as well. In fact there was a company that sold sheets for beds and the like that one could do for kids and crafts. Loads of fun.
Anyway, if there isn't the blizard of the century going on next time, I will come by to see what you guys are doing.