You would be better off building a few bikes from bits you think are nice and compliment each other, to a set price point, then see if they sell, anyone that can tell you a full bike spec and how much they want to spend has already done the research, and would be more likely to do their own.
Lets face it thats what the major manufacturers do, except they have a team of blokes testing and searching for the right bits, working with suppliers etc to create a bike in a certain price bracket, your just doing the same with used stuff.