I would actually try and sell it first. Write up a one page description of what you would be able to offer and see if you can get some potential customers/user

I would actually try and sell it first. Write up a one page description of what you would be able to offer and see if you can get some potential customers/users excited enough to critique it. A strong negative reaction is as useful as a positive one (provided you get criticism that identifies issues/problems). A lukewarm response or the answer "it's not a big problem for me" may indicate the need to let the problem and the solution percolate a little longer.