From my experience the best way to get into this market is free.
You're going to want to do the following:
#1: Write down about 10 things you know a great deal about
#2: Dig up info on what's called "Affiliate Marketing"
#3: Learn how people search online using either Adwords or Search Engine Optimization/Social Media Optimization
Why do I say this? Becasue what I see people do day in and day out is come up with what sounds like a great idea but when they use the net it explodes in their faces.
Working online is fantastic... IF you can figure out what people are looking for.
That's both the blessing and the curse of this industry.
After you jot down those 10 ideas you'll want to use the Google Adwords External Keyword Tool (Just Google it, the URL is huge!)
What this will show you is how people are looking for goods and services.
Now, as an affiliate you can get your feet wet and start to understand the mechanics behind becoming successfull online.
Best part? It's all free.
Some of the most visible and proffitable sites out there are built from blogs. (Free stuff)
Do not spend money on software, websites and/or any sort of development until you know what works and what doesn't work.
Did that make sense?
The entire web has changed in the past few months. If you push for the wrong keywords you could either be buried in obscurity and/or spend a fortune on advertising that does not bring in new customers.
Never try to create a product without first seeing if there's a market for it.
Good luck!