Along with Ataraxy here: What is a prototype? I think you could easily get into a situation where you spend more time in disputes around a misunderstanding of

Along with Ataraxy here: What is a prototype? I think you could easily get into a situation where you spend more time in disputes around a misunderstanding of the deliverable than you do earning income. For example: How many bugs are you going to fix? If the prototype requires a dataset, do you populate one? What if it needs at least two people from every known area code in North America to work (hypothetical here)? You going to populate that too? I think the need is probably there, but you'd really need to target what the deliverable is so there is no room for error.