I'm with Andrew on this - don't cheap out on what seems like a simple task. Make sure also that they properly torque the lug nuts when they mount the wheels. I've seen people be literally unable to remove a wheel with a flat tire after some gorilla used an air gun to tighten the lug nuts. Potentially worse still is widely varying torque settings for each of the 5 lug nuts (well, lug bolts on the Crossfire actually) which can lead to rotor warping.

Talk to the manager of the tire store, let him know your expectations. I'd rather pay $125 and get it done right than $50 and have them scrape a wheel and then not be able to remove them when/if I needed to.