I've gotten this question a bunch of times, and I never quite know how to answer it. I usually just say "from a breeder, and they cost a good bit" or "they costed enough." lol. After that, people tend to back off and not ask specifics.
A while back Ian and I were walking a couple of the dogs around a shopping plaza after a trip to Petsmart, and it was dark out at the time. Some shady looking guy asked us where we bought our dogs, and how much we paid for them because they "looked expensive." It made me REALLY uncomfortable. I just said we bought them for breeders and they cost a good bit. He tried to pry more, but we walked away and left.
One of our neighbors asked if he could buy Tucker, which was also odd.
To me, it's strange when non-dog people ask these questions. I've had people on here send me PMs asking about their breeders and cost, which I have no issues with giving out. It's also something we've talked about at herding lessons, but when you're surrounded by dog people the information is easier to give out.