I have used Costco's refill for both color and black cartridges for my HP OfficeJet 6500. So far so good BUT recognize your printer may still tell you the cartridge needs replacing. Apparently Costco is not "authorized" to reset the sensor chip.
I took my color refills back and they checked the fill to confirm and shared that the printer would still say empty. When I use the "check ink" status button, all the Costco cartridges show low ink warnings.
Printer still work fine, so it looks like I will do what I did before ink sensors--when I get light, missing images, replace the cartridge. ;-).
Price is certainly better than new, especially if you are a high volume user.