I feel your pain. After returning from a 2 week trip to Australia and discovering "crud" on any shot with Sky in it, I was sooo nervous. The local Canon repair places charge anything from $60 to ka-ching ... depending on how honest they are. The CopperHill Kit that other members suggested was the cost of 1 visit to Canon repair. So I figured that I could do what *they* do to clean it.. So I jumped in and bought the kit.
basically, the sensor is nowhere near as sensitive as Canon would have us believe. Just use common sense and don't use heavy equipment on it. Start with the "rocket blower", then go to the "static brush", and finally the "wet pad" - don't use more than 1 or 2 drops per pad!!... It took me like 15 pads to finally get my sensor clean (to my satisfaction) the first attempt. 8 pads the 2nd time. (edit: I haven't read of anyone able to clean this with a wet pad in like 2-3 pads ... most take 10 pads or so ... but they're CHEAP.)
if you can read instructions and take your time, you CAN do this !!! Go CopperHill method.