A lot of your shading and proportions are off in your art, you should really fine tune what you're doing.
Also, you probably have no idea how much advertisement can actually cost. Most advertisements for "games" you see are either for games made for large companies (Shin Megami Tensei IMAGINE), small games with a lot of funding (Adventure Quest, etc.), or scams (
pokemononlinerpg.info).
A major factor in all this is funding. Also, making a commercial RPG maker game is EXTREMELY difficult and in all honesty may not yield the results you want. If you wanna make an independent commercial game, you should start small with simple projects to make a name for yourself, but work with your own base engine rather than RMXP (get yourself a few good programmers or start learning a little programming yourself on the side, there are plenty of online resources to do this for free).
Honestly best of luck, but if you're still a high school student you should really put more focus on your studies first and over ambitious projects such as this later.