A cheaper alternative to the Real Flight would be Clear View (40 dollar download) and since you are getting the DX6i with you mentor...you could get by with one of these to connect it to your PC to use with Clear View
http://www.amazon.com/USB-Flight-Sim.../dp/B000RO7JAI
In the end...all you need the SIM for is just knocking the rust off your thumbs. No real need to spend upwards of 200 bucks for that, right?