You could re-use the bags after cleaning them (pull the spigot and rinse with clean water) or, for peace of mind, simply discard them after single use. They are cheap enough over here when bought in sets of 10 or 20 bags and don't really add a lot to the total cost of the developer.
I don't bother with the cardboard boxes and keep the bags in a plastic container of appropriate size with a hinged lid. I bought the plastic boxes at the local market of a big drugstore chain where they are sold as storage boxes for washing powder or similar. These are robust and can be cleaned easily in case of you spilled some developer (not very likely with the spigot system). Will see if I can post a pic of the setup later. To tap some developer I put the container on its side and close the lid to the point where only the spigot shows, so the bag cannot accidentally fall out of the container while tapping. Make sure the spigot is at the lowest point of the bag while you tap. The plastic container also gives protection in the case of a leak. But this is very unlikely, as the bags as such are quite robust - I once managed to drop one filled with about three liters on the ground and it stayed intact.
BTW, I use this system for all kinds of darkroom chemistry where I have to keep larger stock solutions of several liters (Kodak HCA, RA-4 developer, RA-4 blix etc.) and it works evenly well with all of them. It also saves storage space (plastic boxes can be put on top of each other) compared to bottles, tanks, jugs ...
