I agree with Joss. Nothing would irk me more than to purchase a knife and then return to a makers table -- heck I may just want to chat with the maker or learn something more about the knife or simply praise the maker --only to see a knife I'd have preferred now available. Oh, yes there is something that would irk me more -- to talk with someone and see a knife placed on the makers table and purchased after I had bought the knife I had bought and desire the other knife more. It would be the last purchase I'd make at that makers table.
At the Wolverine show, I spent a lot of time with Karl Anderson after I had bought his knife on both days of the show. I also spent more time with the Tomahawk maker after making a purchase.
The table I did not spend more time at except to take a couple photos was one where there were no prices and the knife I liked was still there at the end of the show. Since then I have spent many times as much as I learned that knife to cost but not visible at all times.
Marketing is based on the 4 P's. Product, Promotion, Place and Price. One of the nicest ways to display a price is to create business card sized cards with all the info about the knife and the price clearly stated. When the sale is consumated, pass the card to the purchaser so he has all the info needed for record keeping. This same card could then be passed on to another collector if the knife is resold.