decent printers start from as little as $326 and go up to $3000

Often the printer is considerably less important than how it's used.

How can I learn more about 3D printing and entrepreneurship based on it?
Like everything in life there are no shortcuts. You learn by reading and studying the subject.
There are thousands or articles, websites and blogs online that will no doubt teach you everything you'd care to know.

But nobody can read them for you :-)

The easiest way would be to buy a decent but cheap printer and just start using it.
Cheapest one that's likely to do the job at the moment is the wanhao duplicator i3.
http://wanhaousa.com/products/duplicator-i3-steel-frame

It's almost a rule of thumb that the cheaper the printer, the more you'll need to learn to use it properly.
And that's no bad thing.