(FORTUNE Small Business) – To the untrained eye, Matt Mankins could be mistaken for someone in the bookstore business. After all, he did open Lorem Ipsum Books this year in Cambridge, Mass. But retailing isn't the 29-year-old's primary goal. Mankins needed the store to test pricing and inventory software he hopes to market to other independent booksellers. He originally wrote the software to automate his personal effort to peddle 500 of his own books on the Internet. Then Mankins realized he had created a program that any used-book retailer could use to double as an online merchant. After observing customers, Mankins scrapped an idea he had about pricing items in real time, using the software's up-to-the-second determinations of supply and demand. "Customers aren't ready for that, and the laws don't allow it," says Mankins, who will start selling the software by year-end. — I.M.