Can you get them to pay for your product now? Ask your customers to pre-pay right now for a few months of service (at a discounted rate).

If you have even 20 customers willing to prepay $49 a month for 6 months of service you'd have $5,880 in your pocket. You just validated your idea and you have money to build the MVP.

Feel free to email me to talk more: http://blog.goodsense.io/contact/