I've seen very few 24 exposure 35mm films in the shops these days, and certainly the Kodak and Fuji professional films I tend to use are only manufactured in 36 exposures and I in fact never shoot more than 34 exposures on 36 exposure film because it avoids pulling the attached film end out of the cassette because of a bad experience I had many years ago when the film was pulled out in the middle of shooting a wedding.
I bought a bunch of that wallmart cheap fuji 200 speed stuff and its all 24 exp. I rarely use it because developing it is 50% more than 36 exp rolls. My lab went from $3.50 to $5 just after I bought it.