There's a trend in top MBA programs called entrepreneurship through acquisition (ETA) where you raise money to buy a business that you acquire through a mixture of debt and equity. Basically lets MBAs skip the building phase of building a small business and go right into operating it.

I run a small business on the side, and although I did a ton of preparatory reading and learning not much of it was useful in retrospect. Most of it you learn by doing and it's not that hard to learn. The top three things that were useful to me to learn were sales, basic accounting and how to read financial statements, and what metrics to track/manage with. You can learn the basics for all of those in less than a month.

My advice is just start. You are probably wrong about what the market wants unless you are selling a product or service that you know there is already demand for. Figure out what it is you're offering and try selling it to people. If they want it you figure out how to make it better, if they don't you try something else.

Edit: I had wanted to start a business for a long time. I thought I needed some tricky new idea to be successful. That's really hard to come up with since most new ideas are bad or are too hard to sell/explain to people. In my case it was also a form of procrastination since I had to wait for the right idea. Things got easier when I just picked an existing problem/industry and decided to do that with my own proprietary software to make it easier for me. I know a guy making a couple million a year from owning multiple tanning salons. There's a lot of opportunity out there that doesn't require any special insight.