Some of the lower priced mountain bikes come with a Plastic chainguard as part of the crankset,
they drop that for the higher priced groups, what is the largest chainring size, ?
44 and there are several to choose from.. 4 bolt?
my local bike store doesnt carry chain guards.
have you asked to see what they can order from their distributors ?
no shop can carry one of everything, all the time.