You can generally find butane just about anywhere, but if you are really having trouble, go to a cigar shop. Any drug store sells it in a can, looks like a small aerosol can.
Additionally, does Walmart sell butane? Ronson Multi-Fill Ultra Butane Fuel - Walmart.com.
Also asked, does CVS carry butane?
Ronson Ultra Butane Fuel (2.75 oz) from CVS Pharmacy® - Instacart.
Does Target sell butane?
Coleman Butane/Propane Mix Liquid Fuel : Target. Try Same Day Delivery for free!