I've considered this topic in-depth. I've gotten pretty good at making graphics, mapping, and writing scripts (to include C++ for DLL files), so I know what I'm doing with RMXP.
The problem, is the audience. You have to appeal to gamers with either older computers (meaning they don't have the money to upgrade), or who really appreciate classic gaming (generally won't pay for games). So, you have to appeal to another niche in order to attract people. These niches usually don't have many games that appeal to these people. Really, it's bout being intelligent with your marketing.
I would never charge more than $10-$20 for an RM game, and I rarely have to pay for my own resources. I make my own graphics, and I write my own scripts. I have a friend who composes music and allows me to request whatever I want, as he loves it as a hobby and doesn't care about me using in projects that I make money from.
Generally, you are going to have to ask yourself: "Would I pay for my game?" and if you would, chances are, someone else would. You just have to remember that you are appealing to certain niches, and going into direct competition with games like Final Fantasy, or Zelda isn't going to get you very many fans, as your game WILL NOT compare to the newer releases in that genre.
Choose a genre, or a niche that doesn't have a lot of high brow competition, and you will go a lot farther.