
I never took deposits, preferring to keep my rights to where the puppy went and to whom, right up to the day they left me. When we bought our Whippet, after 2 previous visits and nearing the time when I'd actually collect her, I paid half her cost to help her breeder defray her costs and actually make it less painful to hand over the full amount in one go. This was back in 2009 when she cost £400 - for pick bitch too.
With all that's going on with litters out there at the moment, there is NO WAY I'd be buying a puppy unless I really knew the breeder (and so she me too!).
On the other hand, I have made a deposit payment to hold a second-hand car I am buying (from my local Dealership) so the car is taken off the market! Note - CAR, not PUPPY!!!