Don't skimp.
Avoid the cheap hardware store crap.
Check your local
tobacco/pipe
shop.
Higher end butane like "Vector" brand will make your torch last longer.
Cheap butane contains higher amounts of Mercaptan. Mercaptans are added to butane so that you can smell leaks.
It's nasty stuff and will clog the tips of torches and expensive lighters.
A cheap alternative is "Power" brand 5x refined butane. It's cheaper than Vector and is very clean burning.