Milage & Maintenance

Last week I took my car into the mechanic. She was 10,000 miles overdue for an oil change. Theoreticaly speaking I've put the same amount of mileage on myself. I guess this means I should take myself to the clinic for my mileage in maintenance checkup. Which brings me to my current query... why do I feel okay to spend over 300 dollars for my car but it bothers me to layout 15 for me?
Just a random thought for the day...