You should be able to check the cost on their website.
http://www.minuteclinic.com/services/$79-$89 for a minor illness/injury exam is not cheap.
It looks like they're more about providing walk-in health care for minor stuff outside of standard hours than they are about making healthcare cheaper.
Going back a decade or so, a few doctors tried to launch 24/7 medical centres here and they failed spectacularly. Even though most doctors here have a locum service which will do after hours home visits, people are still inclined to either wait stuff out if it happens out of hours or regard it as "urgent" and use the emergency room.
The minute clinics sound OK for stuff which doesn't require seeing an actual doctor, but I guess people need to decide in advance that they probably don't need to see a physician before they'll choose to use a minute clinic (I wonder whether there'd be an insurance hassle if you did need to go and see a physician because the minute clinic couldn't handle your condition - would your insurance pay for both visits).
