I use these from McMaster on my CO2 lines. Food grade and very inexpensive. They also have one that has an auto shutoff valve when disconnected. I think that one is ~$5. I get my CO2 and beer lines from Micromatic.
5923K72 NSF WHITE ACETAL QUICK-DISCONNECT TUBE CPLG, PLUG, 3/8" TUBE ID, 1/4" COUPLER, STRAIGHT THRU 1 EA 1.32
5923K42 NSF WHITE ACETAL QUICK-DISCONNECT TUBE CPLG, SOCKET, 3/8" TUBE ID, 1/4" COUPLER, STRIAGHT THRU
I have one European beer tap that uses Guest fittings and it does'nt leak beer at 12 PSI.
I made a totally ghetto 4 line manifold just using some 3/8 copper tubing and 3 tees and soldered it up. No valves, but this is only in use for parties and then disconnected.
In my kergerator manifold I used 1/2 copper pipe with Tees again and soldered on threaded adapters and bought some valves (Kobalt?) from Lowes in the compressor accesory section for ~$5 each. I already had the barbed fittings for the gas lines