Why not ask around your marketing/market research departments? If you must DIY, here are some suggestions: * Find the (estimated) number of users of the gener

Why not ask around your marketing/market research departments? If you must DIY, here are some suggestions: * Find the (estimated) number of users of the general product category (I'm sure googling will lead you to authentic sources publishing such data for your segment) and then estimate what percentage of this could be the potential users. * Make a landing page describing the product in general and collect leads (to drive traffic to this, email your contacts who could be interested, request them to invite others, announce/post it on a few relevant forums/blogs etc.). Track the conversion rate and extrapolate it against the total category user base. -HTH