...and check the business printers. Yes, they're more expensive, but they're built for the task and you can check the output ratings to make your comparisons from.
Just an example, we recently purchased an Okidata C6050 for our office which has a similar workload level. (55,000 page monthly duty cycle.) We needed a color laserjet which also had a parallel printer port and such tools aren't easily found. If I remember correctly, it was about $450 US. So far, although we're probably putting about 2,000 pages a month through it, it's doing fine for about 4 months.
Point is.. there are a number out there but you'll want to check the business machines for their duty cycle ratings.
Hope this helps.
I've purchased two HP Officejet Pro L7680's and both have died on me in about one months time. I've contacted HP and they've told me all they can suggest is that we purchase a refurbished unit from them. I've done a little research and honestly just can't find any printers that are advertised to handle "heavy" work-loads (several thousand sheets printed every few months).
I'm hoping somebody here has a printer they have experience with a printer that has been reliable and they have personally used or seen which prints thousands of documents every month or so without breaking down. Finding a printer that is compatible with a Continuous Ink Supply System or has cartridges that can be self-refilled would be a true blessing. Any feedback or suggestions would be greatly appreciated. Thanks!