Intertap. Get the SS ones. $45 or $65 for flow control ones.
I've just finished up my build. $50 for fridge of gumtree, 2 x Intertaps, 2 x 100mm SS shanks, 2.6kg CO2 bottle, 3 x 19l cornelius kegs. Can fit 3 kegs in if I need, just have to modify the plastic on the door. But I just have my 4l...