I have an HL-5150D and when it was time to replace the starter cartridge I found that Amazon.com had the best price for the high yield version. It was about $65 for a new Brother cartridge. I wanted the high yield version as a base becuase, at the time, I intended to refill it several times with toner from eBay when it ran out. Since I am still using this cartridge I'm not really sure about third party toner quality, however given the print quality with the geniune cartrige I may just purchase a new one when this one runs out. The difference in price may not be worth the possibility of damaging the printer.
I'm a little leery of the 3rd party stuff myself, no sense ***** up my printer to save $20.00. I just ordered a high yield cartridge from Amazon for $69.00