For 7 or 8 years now i have been refilling my cartridges. I have used the same cartridge for over 2 years now. I fill it about twice a week.
I save over £200 a year this way.
You can get refill kits in (UK) supermarkets. And Epson chip zappers.
When I have run out of ink altogether in the past I have used fountain pen Ink.
I think the cartridge industry is big con.