After wasting nearly 3 months with 5 off-brand recycled toner cartridges, I've decided to come back to original Brother cartridges. From a price standpoint, Amazon pretty much has the best price for these (at least this model, which is just slightly more expensive than off-brand recycled models).
Back in the days of inkjet printers, I always used cheap refillable cartridges, but with toner, at least for my printer (HL4040CDN), off-brand toners have just been headaches (2 brands the cartridges were already leaking as I took them out of their bag, 1 brand left a mess of black powder everywhere in my printer and had to have it repaired, and 2 other brands the colors were just faded).