There is no valuation until you sell something. An idea or a company is only worth what its sales are. Once you have your initials sales, sales strategy and forecasting length (ie 9 months from first customer lead to close) then you have a formula for valuation. Valuation for start-ups is generally 3.5 x last years sales model should be the growth factor. When you are looking for investors, you will want to have atleast 9-18 months of SALES, not just pipeline and they will be looking at 5x revenue for a 3-5 year payback.