I suggest trying to talk to potential customers and possibly making your first sales for even less than the full $12K in proposed startup costs.

For example: rent the camera for 1 day. Take the photos on foot, on a couple of residential blocks and a couple of commercial blocks. Approach occupants door-to-door, or via a low-res mailer with followup call/knock. Ask for a higher price -- but be flexible, you're trying to learn the right price.

If response is positive, there are lots of ways you could fund expansion beyond just Mr. Cuban -- including grants and investments from 'social' or 'green' enterprise groups.