My wife bought an old antique cider press a few months back and we decided to go ahead and use it (as opposed to "preserve" it). So far, we've made a 5 gallon batch of cider and a 5 gallon batch of perry. It took about 2 bushels to make a 5 gallon batch of cider and the same for the perry. According to Wikipedia, a bushel is 35.23907017 liters of fruit. I don't feel like doing the math since I've had a few tonight and would probably get it wrong, but this might point you in the right direction.
How exactly are you planning on turning the apples into juice? If you don't have a press or a juicer, it might be mighty hard to get a good yield. What kind of yeast do you plan on using? Do you plan on adding sugar of any type?
Oh man, don't use a juicer. You'll regret it, it'll take way too long and be too much work! What part of the country do you live? If you live in Apple growing country, try to find a press at a farm that will do your apples or an independent one.
I go to a local press, did about 9 bu, got over 25 gallons, I think (not exactly sure)...I might have posted it a while back. The thing is with a press, the more you fill it the better your yield, at least with a big press. Dunno about the small hand crank ones, but I imagine it would be true to a degree as well.