My expense to clean the sensor on my 20D last February was $20 for the cleaning plus $30 each way for shipping. I've invested in a sensor cleaning kit since and found a local shop, in business since the film days, who can do what I can't handle for under $50. I'd prefer to pay the extra money when I need a cleaning and have my camera in my hands in 48 hours.
5D II, 7D, 40D, 20D (IR)
28-300 f/3.5-5.6L, 35-350 f/3.5-5.6L, 70-200 f/2.8L, 70-200 f/4L IS, 200 f/2.8L, 135 f/2L, 100 f/2.8L, 24-105 f/4L IS, 85 f/1.8, EF-S 17-55 f/2.8 IS, EF-S 15-85 f/3.5-5.6 IS