Of course I agree with you that what you're saying is what you _should_ do. But will you be able to convince the potential client to pay for that? Not on your

Of course I agree with you that what you're saying is what you _should_ do. But will you be able to convince the potential client to pay for that? Not on your life. Either they already know they need a spec, in which case they're not searching for a prototyper, or they "know" they don't need one. I mean, I suppose you could raise your fee to $7k or whatever to cover the cost to spec it out, and say "prototypes for $7k". But speccing out an arbitrary project is just so vague and has so many dependencies on the client. Will they answer your design questions in an hour? In a day? In a month? How are you going to juggle all the client's delays and that? And by the time you've thought through all that, you're no longer a turnkey prototype delivery service, but more of a traditional design/development firm. Nothing wrong with that of course, just not what the OP had in mind.