Spent some time driving around looking for work the last few days and I found a company I never noticed before. WA Drierite. THey sell industrial water liquid absorption products. Some of it looked like it might be pretty good for putting in safes and such. Didin't price match much, but was guessing buying direct from them might be cheaper than buying from Brownells and such. The following has ten pounds for $26 which seems like a lot to me. Could probably wait a few year before you had to recharge in the oven.
https://secure.drierite.com/catalog3/page15a.cfm
Looked at the MSDS and it didn't seem so bad, although MSDS sheets only show what has been proven. Any chemists around know if this is the same stuff? Might be able to get some on the cheap.