Refill ink cartridges, not a good idea. Too messy. I gave up that idea years ago due to permanently coloured fingers.
Much easier and just as cheap to use compatible cartridges.
You say: "A CISS system is an excellent idea but my printing needs are not that great."
That sounds to me like you are not using your printer enough which could be the problem.
I have 3 Epson printers, all fitted with a CIS system but I always run a print test at least once a week just to keep them working properly.