Well I'm late for work so I didn't have time to look around much, but here Propylene Glycol Gl - Neeps Lawn and Garden is a gallon of PG for 26 bucks, you should be good with that for a while, and it is USP grade (you aren't going to find it any purer, this is medical grade). And Misty all of the symptoms you listed have been observed, I remember reading them on the tests they did to check the LD-50 (how much they had to inject before the poor critter died) of the stuff, and these were symptoms noted shortly before death or on amounts so high if you injected someone with this much pure water, they would become delirious due to their blood being diluted so heavily. However, they have done long term studies exposing rats to very high concentrations of pg vapors for 6 hours a day for 2 years, and done the traditional battery of mutagen tests (the ones that were used when they found VG's possible mutagen action) and no irreversible long term damage or mutation was found (the ones exposed to the highest concentrations had some symptoms from the nasal passages being overly-dried out, which they also observed healed almost completely on the 2 day breaks they took on the weekends). I will send you the full report later and I am leaving a lot out but I was supposed to leave for work 11 min ago 
bye bye
bye bye
