How much would a truck load full of limbs chip down to using a chipper?

[BigBadWolf]

Just a rough guess? Reason I'm asking is I'm thinking about buying a chipper and doing residential shipping since my city doesn't pick up brush/limbs/yearly prunings. I don't have a place to put the chippings so I would be putting the chips in large garbage bags (they said they'd haul those off) but I don't have any idea how small a big pile of limbs (truck size) would chip down to. Any idea? Does this sound like a decent way to make some extra money?