Hah. I did something similar a while ago, but I also did full saturated salt solution humidity calibration. It's very simple to do: get several different salts, create a saturated solution in a sealed container, and observe the humidity there.

The best sensor in my tests was CentraLite 3310-G. It was the only one actually precise to 1% of RH and 0.1C They are also pretty robust and long-lasting.