Something on disk is going to cost you around $200 for anything decent (RF. AFPD5 etc.) and they aren't "risk free" as in once you buy it you are stuck with it if you don't like it or it doesn't work on your computer. Quite an expensive risk IMHO.
To get started all you need is a used TX with a trainer port, a USB cable for it (under $10 ebay) and download FMS (free).