The companies Tim Litle and Amy Emery own look very different. Litle runs a nine-year-old business that has grown fast enough to make the Inc. 500 twice and today has 125 employees and more than $100 million in sales. Emery, meanwhile, is still answering the phone at Antoni Products, her two-year-old, one-person mail-order business, which sells toys for special-needs children. Yet ask about either company's experiences with customized software and a common theme emerges: on any scale, custom software can be complicated.

Litle's business, in Salem, N.H., processes mail-order companies' credit-card orders. Each day Litle & Co. faxes its customers information on the previous day's credit-card transactions. By 1993 Litle & Co. was doing so much business that two people were manually feeding fax machines virtually all day. The company first attempted to automate the faxing with a custom solution -- one that required three person-months of in-house software programming, plus $30,000 in new equipment. The result? A system that was unacceptably slow. Litle & Co. soon began looking for a replacement, and a project team under the direction of operations vice-president George White swapped the proprietary system for a $20,000 turnkey fax server, which has delivered great savings. The moral of the story, according to White? "If you can buy it, don't build it."

On the other hand, as companies demand more specialized and more responsive computer systems, off-the-shelf software won't always do. Here's what managers in small companies say about the process of custom programming:

It will take more time and more money than you expect. When Skyline Displays, in Burnsville, Minn., set out to automate the designing and order processing of trade-show booths, software development took a year longer than anticipated -- and don't even ask about the cost. The undertaking, says director of production control Dan Poff, was far more complex than it at first appeared.

Complexity is an issue for even a small project: Emery, who wanted a program simply to put the text of children's books on computer, was amazed at the number of changes she and her programmer had to work through. "Every time I thought it was finished, we found a glitch," she says.

Make sure you know what you want. That sounds obvious, but when it comes to the program's details, people in your company may have differing priorities -- even if they agree on the big picture. Dale Uhl of WASTREN, a $9.6-million waste-management business in Idaho Falls, Idaho, discovered that while working with an outside company on customized management software. Uhl says he and his staff gave the programmers mixed signals, so the project is taking longer than it should.