(FORTUNE Small Business) – One beauty of the magazine business is that customers pay in advance. The money for a full year's subscription rolls in before the publisher has to deliver a single issue. Are you stuck in an industry where that's not possible? Don't be so sure. Judy DeLello, founder of Informed Systems, a tech firm in Bluebell, Pa., is bucking convention by offering her customers a chance to buy consulting hours in advance.

"When I started doing this, it was unheard-of, and everyone said, 'You can't do that,'" she recalls. Today some 65% of her clients prepay for the company's guidance on installing and using Great Plains, Microsoft's management software. Now that inflation fears have revived, paying upfront is even more appealing. "If Informed's rates go up, I've already locked in a lower price," explains customer Marie Gunning, a controller for PSC Info Group, an Oaks, Pa., firm that manages collection letters and claim forms for hospitals.

The price break can be substantial--as much as 20% off Informed's $175-an-hour rate on a purchase of 100 hours--but the surprise is that customers like prepaying for other reasons too. They find Informed's monthly statement, which shows services used during the past three, six, or nine months, a useful tool for analyzing spending and forecasting future consulting needs.

Asking for cash upfront enabled DeLello to launch Informed in 1990 without borrowing a cent. And it has fueled expansion, allowing her to bring on new consultants, who may need three to six months of training before they begin generating revenue. The profitable firm now has about $1.5 million in revenue and eight employees. To spur more clients to part with their cash early, DeLello has eliminated travel charges on bulk consulting purchases and offers discounts on the business forms and checks the company sells. "In nine years we've never had a prepaying client go back to hour-by-hour purchases," she says.