We switched to a vendor at work a few years ago to maintain our laser printers (about 800 of them). They used some junk toner and within 2 months, most of our printers were a mess. They had to come in and clean every printer and replace the junk with real cartridges at their own cost.
I know there are some decent brands of refurbished cartridges out there, but there is alot of junk as well.
Sorry I can't point you to a specific brand.