It isn't about the brand name, it is about quality. I prefer quality parts over cheap knock offs that don't last. I don't like spending a lot of money on good mirrors either, but prefer not to save some money and then complain when I have to turn around and buy new mirrors again, because the ones that I just bought a few months ago are broken already. You can usually find some that someone is selling on e-bay one at a time, it is painful, but you don't have to spend full price at a dealer. Just my $.02...The ones I got were aftermarket MCS brand (AU$65 a piece), where as Genuine Kwaka AU$170 a piece. The way I justified it was that the replacement cost of my Yammie mirror was AU$150.
(Australian Retail prices noted)
Had nosey at someone's 250 Ninja parked at the shops the other day and there doesn't appear to be any difference.
I am a tight arse -if brand names are your thing and you dont mind spending more -go for it