I think many folks use a laser printer. Those I learned to fill also. You buy a container of the black stuff...and there's a plug to remove and replace. You pour in the stuff. Easy as pie.
Most cartridges have a chip in them that determines how many prints have been made, reloading will not work.
There are hacks to reset the counts on the cartridges but easiest to just have a professional refill them.
I read somewhere last week that Keureg coffee makers were going to chip there coffee pot so that only their original unused cartridges will work.
I bought a Brother laser printer with fax, scanner, wifi, all the goodies for a little over $200.00, and bought a 2,600 page cartridge for $8.39. They ran behind a while on drivers for the Mac but finally came through.