I've used the cartridges myself, which look like tiny wax cubes, in Xerox Phaser 8560 printers. If you're unfamiliar with solid ink, they're pretty easy to use.

The Phaser 7500/DN’s huge toner cartridges are incredibly cheap per page. The 19,800-page black cartridge (one size only) costs $330 or 1.7 cents per page.

The Phaser 3600/N buzzed through our text-based speed tests at a rate of 35.5 pages per minute (ppm)–a bit short of the 40 ppm rate that Xerox promises, but still quite fast.