You should probably find out the demand first....market research. If you do the market research you may be surprised at the level of interest. Or underwhelmed and realize it's not worth quitting your day job over.

Then figure out how long it would be until you have a product that you can sell for something. Even if it isn't the whole shabang (which will deliver more on the money but will require non-stop work for months). Perhaps you allow people to sign up and pay $X / month for the database of information that you are collecting to create your real product. Like if you have a database of names and addresses for X location, you can sell access to that database for $100/month. If you have another database of maps of the area with another data point, you sell that for another $100/month.

You'll need to have all these for yourself anyways. Then you can at least have some funds to hold you over until you are done with the number crunching, analysis, etc.

I have no idea if this is feasible for your situation or not. I have no idea what I'm really talking about.

Do you have any under or unemployed friends? Is it something you can oversee while others do the dirty work? LLC with a couple contracts and split ownership can be mighty appealing to a lot of people these days.