Upload & Sell: Off
I can certainly see sending a body for service, but for cleaning??
It's really easy to do, and you never know when you need to clean it "right now". Buy the materials and learn, much more convenient and lets you clean any time it's necessary.
Besides, The camera body chamber is not hermetically sealed. The repair center could clean the sensor spotless, but with the normal jostling of packaging and shipping dislodge a dust bunny or two so when you get it back you still have dust bunnies.