Market size and direction, who already sells it and at what price, what buyers ask, and where the gap is — every figure traced to a source.
Research the market for what I'm thinking of selling. Cover four things and be straight about what you couldn't find: how big this market is and which way it's moving, who already sells it and what they charge, what buyers ask and complain about before they buy, and where the gap is. Name the publisher of every figure, and tell me plainly where there wasn't enough published to say.