A few local vineyards here do some version of the following for white-wine-making home gamers:
Sell the grapes and you pick up chilled, racked, settled, ready to ferment juice. No added charge for processing. Prices are roughly $1.50/lb, and the conversion is roughly 18lbs of grapes per gal of juice. Beer kegs work great for this and at 15.5 gal you need to buy 280lbs of fruit - $420. For the equivalent of a 6 gal bucket that'd be, what, call it $160 or $27/gal. This is machine-harvested fruit.
How they sell 6 gals of juice for $50 or $8/gal I have no idea.