Complex technology and staunch patent enforcement help keep ink prices high. Still, some low-cost alternatives can be found.
The idea has been around since King C. Gillette first crafted his disposable razor: Hook customers by selling the main item for cheap and then mark up the price of blades.
It's a century-old business model that today's tech industry has taken to heart.
Hand out free cellphones, profit off the subscription fees. Lose money on each video-game console, earn it back on the games themselves.
But recently, computer printer manufacturers have come under fire for allegedly pushing the plan too far. Some customers and industry analysts charge that inkjet companies are using their influence to unfairly distort the price of replacement ink cartridges and shut out off-brand competitors.
"What I've found over the past few years is that ink itself is a very good commodity to be in," says Tom Merritt, executive editor of CNET, a technology news and reviews website based in San Francisco.
High-quality ink is expensive to make. It's packaged in specially designed cartridges that are difficult for others to replicate. And it comes saddled with patents and copyrights that the companies staunchly defend.
"But what's happening is that [printer manufacturers] have gotten so aggressive now in preserving their profits that a lot of people worry they are clinging too tightly to this minimonopoly," he says.
It's a concern that escalated into an antitrust lawsuit that was filed in Boston last month. The legal complaint accuses Hewlett-Packard of paying Staples $100 million to stop selling off-brand ink cartridges that are compatible in HP printers. Both HP and Staples deny any anticompetitive practices.