Thanks for the links. I'm not planning on building anything right now, but the frustration that lead to me starting this thread might push me in to it one day.

Thanks for the links. I'm not planning on building anything right now, but the frustration that lead to me starting this thread might push me in to it one day. As for the Kano model, I'd take it further and do what I call the Buffer model: price people want something by collecting payment details before you even start building the product.