[T.G]

At 1200-1400C it all burns clean. If your lighter will run on the cheap stuff, and you feel like $1 over the course of a year is a significant savings, then go for it. If anything, the more refined / higher grade butane is just to keep the finicky lighters from clogging. Possibly inhaling a smidge of impurities in the butane isn't really something I concern myself with when I'm smoking a handful of dried, rolled up known carcinogens.

I would avoid the perfumed butanes though.