I have pressed 23 or so kg of apples and crabs into 12l of juice. The yield is not so great cause you lose a bit once you discard the bad 'uns and cut out any obvious nasty bits, and the crabs also don't give as much juice as apples do.
With this I've put down two 5l carboys of juice for cider, and topped up the third with a kilo of honey and some water to make cyser.
Total labour input: about two hours to obtain the apples (foraging in the park, pick up from inlaws, harvesting our tree), and about 4 hours to process and press and clean up. Total dollar cost: zero. Satisfaction: immense.
I might have it in me to get one more batch done this year.
#cider