Thanks for all the great feedback- will def look into Brother- and I hadn't considered refilling laser toner cartridges- duh- can't be any more messy than refilling liquid cartridges.
Toner powder is a bit messier, especially when you clean out the waste toner and remaining old toner. Just be careful, take it outside, and wear an effective dust mask. If you do go Brother TN420/450, the linked PDF I gave in my second post is the official technical way to refurbish and refill a Brother toner cartridge, including resetting the gear wheel which is necessary. You can usually get about four-five refills before something breaks. One thing, it can take longer than an inkjet refill to do, so if you do refill, always keep your next one ready when you
do run out of toner. The nice thing about toner is that it doesn't go bad, so refill in advance.
Final little pro tip for successful and proper toner refilling: Not all toners are identical. On your first refill after an OEM Brother cartridge with an aftermarket refill, or if you switch toner refill providers, do your best to clean out all of the old toner before adding the new. This will minimize the patchiness in printing that you can sometimes get when you mix toners.
Lastly, even if you don't feel like taking on refilling cartridges, there's no shame in that. The TN450 cartridge is the better deal. Stay away from aftermarket cartridges, though. They tend to leak toner and degrade overall print quality. If you do go aftermarket, use authentic refilled/re-manufactured Brother cartridges instead. The print quality will be higher, and the lifespan of the printer will be better for it.