An empty cartridge shouldn't stop you scanning documents and photos but it will stop you printing anything until the cartridge is replaced. I won't use compatible inks as that throws up warning messages and the quality is unlikely to be up to that of genuine Epsom products. I tend to buy my genuine Epsom ink off eBay and pay up to £20 for a complete set of 4. I don't consider that a rip-off.
However if you want to buy cheap you'll probably find out it works out more expensive in the long run.
ChicksFan
March 2015