SGF, Supreme Grumble Framer
We use gentle redirection to steer them away from this sort of thing. Since we have a visualization system and a POS, we say "Here, let us print out a picture of the mockup for you... or would you rather have us email it to you?". As for their taking down part numbers, we quickly whisk the samples away to the POS and work up the quote. We then say "It's okay, we've got all the information here in the system. When you're ready we can pull up the quote and turn it into an order". This makes it rather awkward for them to say "but, but, we want the part numbers!"How about the ones who take all your time designing and pricing and then "secretly" start writing down all your frame numbers and start taking pictures of them with their cell phones. Then they say, BUT I HAVE TO ASK MY HUSBAND, thanks for your time, and they leave (to go price them elsewhere).
I'm trying to figure out a nice way of explaining to those people that it makes it hard for us to do our best consulting with them when we're worried about them stealing our designs.