The first thing that I'd do is a SWOT analysis. What are Strengths of your idea (eg. it's completely unique), what are the Weaknesses (eg. technical problems), Opportunities (eg. market size) and Threats (eg. competitors).

This will help form the basis of your thinking in developing a business plan around which a key component is the cashflow. You can do all of this without actually spending large sums of cash.

Lastly, in my own company we have a saying, "Build the rusty mini-bike before the Harley Davidson." In other words, do everything manually and don't automate a thing and see if your idea actually works as a business concept. I've seen too many businesses try and build the ultimate solution right out of the gate only to discover that they didn't actually have a market for the product.

Whatever you do.....define the rusty mini-bike and work out the cycle from advertising, through to customer purchasing your product/service. Most importantly.....are they coming back.