For touring, folding tyres save some weight, are easier to fit, easier to carry as a spare ... but yes they do cost more.
I use cheaper wire bead tyres on my commuter bike, but use folding tyres for touring and long day rides.
Minimising spinning weight means less fatigue and more fun for more distance travelled on tour. Hills, wind and luggage provide enough workload without adding tyre weight and rolling resistance into the mix.