I am not sure if RMXP's license is limited to selling the game or to making money off it. But fact is that if they are making money off it and they haven't bought RMXP, that is illegal, because not buying RMXP is illegal. Once you buy RMXP, I think you can do with your game as you please.
As for MS, read the license of VC Express and VC# Express (and most probably VB Express as well). Both licenses allow you to sell your apps without having to pay anything.