If you take the tires and rims (off the bike) to Tousley, they usually will do the set for under $40.
Their policy is that if you didn't buy the tires from them, it's an extra $10 per tire or something like that, but I've yet to get charged that.
In case you need directions (from downtown St Paul), 35E North to Co Rd E (first exit north of 694). Turn right on Co Rd E and go about 6-7 blocks. You'll see it on your right side. you can't miss it.