Do it yourself, it is not difficult as stated by Neuro.
Try a puffer brush, the one with the cap to make a jet of air, I use one of these, I have 2 sizes, one about 1 1/2 inches dia one about 2 inches dia bulb, a jet of air from either of these usually does the job, I do not use the brushes on the sensor, just the puff of air they generate, much safer than canned air.
More stubborn marks are attacked with visible dust wet swabs with vdust plus liquid, follow the clear instructions for quantity of liquid precisely! I think I have only needed to wet clean my 300D and 40D sensors once, the 7D just puffer for dust so far, the smaller puffer brush usually has enough puff but some times the higher volume and velocity from the bigger brush are needed, the smaller one is easier to see past whilst cleaning!
Avoid going in to the body with the puffer as they can wiggle when squeezed!
I did all of the above before finding the cleaning regime listed by Roger at lens rentals in the blog Neuro links to.
My kit works, I'm absolutely positive Roger's kit is better than mine for any and all eventuallities, would I change what I have?
No not for the oh so infrequent clean that I do, if I was cleaning many sensors everyday where someone could come back to me cursing and swearing about a spec of dust ruining his once in a lifetime photo op, hell yes I'd do it the Roger way!