It's 10 bucks to dismount and mount a tire, then another 5-10 to balance it at my work.
You should see the cost of wheel weights now a days too, stuff isnt cheap anymore. Even through the vendors we use it's alot of money, some boxes are anywhere from $5-15 a box depending on size of the weight and you only get 25 in a box. So on some cars you may use 1/4 of that box on a set of 4. Figure most BIG chain shops only make 5-10% off the tire sale if that, we end up selling most for $5-10 over our cost, so we have to make something back off of wheel weight charges and disposal of the old tires. We may charge you 3-4 bucks a tires but it costs us $1-1.50 per tire to have a company come out and take them away.