it depends on customer's level of pain.

I'm currently working on a solution which many potential customers suggested they will test it right away once it's ready, and promised to get me 10 more customers in order to encourage me to work on it full time.

However, I did not get paid yet before the product is ready.

You need to find a solution where it improves the productivity of a business or a person by 10 folds.

for exmaple, if cars are not invented yet, and you promised a farmer with the invention of the truck, so they can take their produce to the city 10 times faster, and increase their productivity and revenue by 10 times. in this case, they will pay you to develop the "truck"