Sophie our 4 year old recently had pups and we wouldnt let any of them go untill 8 weeks.
It seemed a good time for both mum and the pups. Any earlier and the pups would not have been as prepared to deal with the change of home and loss of mum and litter mates.
The costs of keeping puppies until at least 8 weeks should never come into the equation if the breeder is reputable. Always it should be whats best for the pups and the mum.
That having been said, I wanted to keep all 7 of our pups but the boss only let me keep 2
Steve