Place it in a high-traffic spotsuch as your front window, near your point-of-sale, or in your play areato maximize visibility
The winning bidders can choose to keep the pack they buy sealed, but if the high-rolling collectors let Martinez open them up at the convention, they can have them professionally graded for free
While six mana is enough that I would be surprised if this ability were the primary reason people played the card, it can do some pretty powerful things in the late game and opens up the possibility of Honored Knight-Captain seeing play in an equipment deck
Paying the prototype cost of a card changes its physical mana cost, so you use that new mana cost to determine the mana value
I dont think either deck has anything as essential in it as the bounce package from Rise of the Floodborns starter deck, but the Amber/Emerald deck has a nice pile of cards that I think will see play
Don't trust your feelings