Do you have a Surface RT but want to get the Surface Pro without selling your Surface RT? Neowin reports that Microsoft is running a trade-in program for the Surface Pro. You must bring in your Surface RT and purchase a Surface Pro in order to get the credit for the trade-in.
You will have to pay the price difference between the RT and the Pro. The RT runs on Windows ARM and can only run Office while the Pro can run legacy x86 and x64 programs.
I would advise you to call your local store before attempting the trade-in. There are reports that some stores will credit your trade-in towards a new Surface Pro while others said they have no such deal in place.