I’ve now bought and used 2 laser printer toner refill kits from TonerRefillKits.com and I’m very happy with them!
It took about 20 minutes to refill my second toner, saving about $50 off a name-brand new toner cartridge. I’ll get it down to 10 minutes with practice. It takes a little bit of disassembly and work but they gave me excellent printed instructions and their website practically screams “If you have ANY questions or problems, call us, we’re here!”
Our family has 2 Brother HL-L2350DW laser printers. They’re pretty good inexpensive printers. (Though last month one just died on me, Brother support walked me through everything but… [sad trombone sounds])
I’ve had mixed experience with inexpensive, off-brand toner cartridges. I forget the details but I think about 70% of my toner purchases from V4Ink on Amazon worked flawlessly.