I've been filling HP color and Black cartridged for years. For $100.00 you can purchase (3-Pints color + 1Pint Black) enough bulk ink to refill cartridges at a small business for over a year. I've filled the Black cartridge seven times before repalcement of the cartridge is necessary and the color five times. I applaud you. I haven't been brave enough to do that, since in the manual that came with my HP printer, it says that doing my own refills voids the warranty. I don't know how they would know that I had done that, but it's made me skittish enough to stay away from that option.
Unless you tell them they won't know.