I bought RPG Maker VX Ace when it was on sale on Steam for half off, and I've dabbled with it a bit. It's quite fun to mess with.
As for buying a game made with one of the RPG Maker engines, yes I would. I love old school style RPGs. I wouldn't care if they only used the base resources that the program gave them.
But of course, I'm the purest type of gamer that will play pretty much any game if I have the money to get it, and they don't have to have the latest newfangled everything. Oh, the game looks too retro or "dated" in style and game-play and that's why you say you can't play it....yeah, get over yourself.
It is sad how many people miss out on great games because they have these mentalities:
1.) It doesn't look right, why didn't they use a better graphics engine(or just plain with the best graphics out there), or make it look like this other game I like.
2.) Oh, it doesn't have that mechanic that makes things so much easier and quicker, like other new games I've played.
3.) Oh, it doesn't do anything new and doesn't innovate, well then it is just rehashed piece of crap.
I just can't stand people like that.