Need "Heavy Workload" Printer Suggestions

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!