I've got one. I always wanted one as a kid and used to love playing the MVS system at the arcade. Of course, the ridiculous expense of the system and games meant I never got one under the Xmas tree.
I bought one a couple of years ago and it is awesome. Yes, some of the games are ridiculously expensive but there are some classics that can be picked up for under £40. In fact, most of the games I remember from the early days of the system (1990-1993) are the cheapest. I'm less interested in the later games (the ones with the huge price-tags) so it hasn't been the most expensive hobby to indulge in.
It all depends on what you want out of the system. For me, classics like Magician Lord, Art of Fighting (one and two) and Fatal Fury Special make it all worth while.