Implement it yourself. Or hire smart people for equity only- easier to do in the Silicon Valley than anywhere else (it's amazing what a single ad in Craigslist can do). Or pay young, super-smart programmers in India for a fraction of your monthly salary- you may not be able to afford it for a whole year, but we're talking about 3 weeks (i.e. iterations) here at a time.
Regardless of the approach, practically every software entrepreneur in the US now has the ability to incrementally implement the features defined by the customer(s) , one iteration at a time. And get valuable feedback. And sooner or later, you'll have a paying customer as long as you stay true to the principles of Agile- "The Customer Is Always Right At The Beginning Of Each Iteration" (apologies to Sam Walton and Kent Beck:).
Alternately, the customer(s) might realize soon enough and declare that the product doesn't have as much value for them as they initially thought - and led the entrepreneur to believe. That is, either they won't buy or the price is not worth the effort for the entrepreneur.
No big deal. The entrepreneurial itch has been scratched, definitively, affordably. He can move on to better things in life, like, umm ... another product?
Software entrepreneurs no longer have to choose either risking getting burnt in order to find out whether their idea has merit or living for the rest of their lives wondering what if.
For more tips for Agile Entrepreneurs, go to www.AgileEntrepreneurs.com