Aftermarket cartridges might work just fine. Plenty of people (including a former employer of mine) used them without problem for quite a long time.
The catch is that there is no guarantee that it is manufactured to the correct specifications. Potential issues regarding toner include:
- Colors are not exactly the same as Brother’s colors. So the color balance of pictures may not look 100% right. You might be able to work around this by generating a custom color profile for the toner and then use it instead of the printer’s built-in color settings.
- The toner might not be ground to the same density. If it is too coarse, you may find less-than-ideal resolution especially on curves, text at small point sizes and halftoning. I don’t know if too-fine toner will cause a problem.
- If the composition doesn’t match, the fuser temperature may not be right for it. If the temperature is too low for the toner, it won’t stick to the paper properly.
Unlike an ink-jet printer, I don’t think low quality toner can cause damage (e.g. clogged heads in ink-jet printers).
If you want to give it a try, I think it should be fine. If the print quality is good enough, stick with it. If not, switch back to genuine toner and accept that that’s how much you’re going to pay.
BTW, be sure to shop around. I’ve found that (for my Brother laser printer) I can get a set of four genuine Brother toner cartridges from Amazon for about $100 less than buying the same set from a retail store like Staples.