Quail take a lot less space to raise than chickens do. Coturnix do well with 1 sq. ft. of space per bird, and that is being generous (for coturnix). Most mine have less than that. 
As others have stated, the coturnix have a very quick turn around. They are not full grown at 6 weeks as stated, but they are almost full size then. Full grown is about 10-12 weeks old, but most start laying eggs at 5-8 weeks old. 
Mine are my money-makers 
 I did not spend any out of pocket cash on feed for my birds last summer, every bag of food bought was from money made off the sale of the coturnix's eggs. About $45-$50 a week. 
I have not processed any of mine (can't kill my BABIES!! 
),  but have sold some extra males to others for a decent price. 
They don't eat as much as chickens do either, though they do need a good quality feed if you want maximum production from them. 
Their feed-to-egg ratio is also lower than for a chicken. I've read that for every 1 lb. of feed a quail eats, it will lay 1 lb.'s worth of eggs. 
They will lay eggs year round, if given supplemental lighting. My jumbo browns are still giving me 3-5 eggs daily, from 8 hens, with no additional lighting. I have a golden that has been laying daily since spring. Most of the others have stopped laying, but I don't give them any light either. 
This summer I was selling eggs for $6 for a day's worth (about 2 dozen), and sold every one. I took some quail to a local auction, 27 birds total, and made $75 off the birds.