My post this thread #47 you have to renew the filters every 6 months so about €100 a year to run but I don't think you'll get a better manual system. If you want any more info just ask. Ideally it needs clean water that isn't cloudy as the more muck in the water the more work the filter has to do and the sooner it gets blocked. Also needs cleaning (just a wipe over with a pan scrubber) every month again more cleaning if the water is dirtier.
Edit - noticed your edit and the filter candles are about 50 euro for 6 months use but can be stored indefinitely. I keep 12 month supply and then rotate that by buying new ones when I use them from stock. Currently the filter candles are in short supply and expensive (not by much and none available with the free postage I normally get) but having a small stock of them allows me to buy them when the prices are at their cheapest.