Most storage places use those high frequency boxes that repel mice (about 4" x 4" x 2") that plug into a 120v outlet. About $10 to $30 at Wal-Mart, Home Depot, Rona, Canadian Tire, etc.
I've used one for 15+ years without any mouse problems.
If you use mouse traps, use a very small amount (size of a kernal of corn) of peanut butter as it works the best. They'll bite the string off a piece of cheese.