Oh boy - disagree with the premise. It's been four months since you started? You haven't failed. It looks like you've been trying to market it to the Internet at large and not targetting your likely user base. Go see some local businesses and see if they are in the mood for a better inventory management system. Get one business using it. Then another. Then another. Build your user base one person at a time. Businesses tend to talk to each other. You say have one paying customer? Great! That proves that somebody is willing to pay for it. Just reconfigure your marketing and target the people who are likely to do so - those with whom you already have a personal connection.