I have just installed my first set of 3rd party color laser toner cartridges from http://ink-hk.com a few days ago and I have to say it's a waste of money.
I have used their black cartridges before which were OK (not as good as the original but alright).
But the color ones are really unacceptable bad. The were full of color dust when I took them out the bag. Everything was full of dust and it was difficult to clean up. After that I installed it and now the pages I am printing are smudged and smeared all the time. Had the cleaning mode running at least 10 times, only little change.
I have had them for a month or two before I installed them, so I am probably out of luck complaining. But for me, it means back to the original expensive HP cartridges :/
For your info, here is the price difference (on that said web site):
full set of 4 colors their own brand: $1020
full set of 4 colors HP original brand: $1980
$1020 down the drain and a lot of cleaning and wasted time.