Buy for $5, sell for $15 means $10 margin. 50% commission paid to student means you pocket $5 per sale. 100 sales per month is $500.
It's not as fun, but you could cold call businesses all day long and try to sell them on a website for $3000. It might take you a couple hundred calls per sale but you'd end up making a whole lot more.
Or, you could find a real legitimate need in the marketplace - a need that people (or businesses) are willing to pay top dollar to solve - and then offer to solve their problem. If you're on this board, maybe you know a thing or two about SEO, landing pages, PPC, marketing, etc. You already have skills that are worth thousands of dollars a month to the right businesses. Forget your current idea, up the ante several notches.