Propane is a bit smelly but very cheap (4 cans $12 Homedepot) and i find adding silicone oil each fill helps with the smell!

(i Use the silicone oil used in R/C suspension - pure and light, if you get a light weight oil that is - can be found at any R/C hobby shop)

Lmao, for some reason I assume this guy got his answer. As it was posted almost 4 years ago.