You're doing the right thing and handling the questions very well. Part of our jobs as responsible breeders is education about how & why we do what we do and they can always go elsewhere if they don't like your answers. Great job!

I always tell them I am breeding the litter for a potential show/breeding prospect(s) for myself, rest are sold on limited reg. as wonderful companions. if they are already talking breeding, you can bet they will do it. I no longer sell any pups to breeding/show homes, too much of a headache policing them to comply with the contract ( show the dog, get "all" health clearances )....if a pup is very nice, "I" keep it!
It is easier to put my pups in great pet homes, and best for the pups too.
you should dismiss these inquiries, better ones will come!

Most of my inquiries come as a result of a litter announcement on my web site. I rarely get generic calls. I document my process there so it is clear up front, so I generally do not get these questions when I talk to them.

I recently had a puppy buyer put it well I thought, as far as "first pick". It is not "first pick that matters, but the right pick of the litter". This was a new buyer to me, and while at first I was hesitant, the more I conversed with him the better I liked him. He told me some preferences (pup was to go to a hunt test home, so drive, and birdiness was most important). The buyer was most willing to let me pick the pup. At 10 weeks, the buyer emailed me back, and said he was so pleased, and that she was already "retrieving" ducks and was so very pleased with herself when she did!

Another buyer of the litter was originally fine with me picking his pup. he stated his preference, and when I said I picked the smaller female for him, he hemoraged. He thought I he was getting a runt. Pfffttttt. I invited him to come see the litter and judge for himself the pup I had picked for him. the buyer could not even see the size difference (it was indeed minicule). She was so birdie with a pheasant wing, that the buyer was instantly pleased and contracted to bring her back for her basic hunt training.

Education is everything!