One way for smiths who have this 'problem' of over-inflated resale 'flippers' - very simple:
Keep selling them at the 'regular' price point non-stop until demand is satisfied.
IE - work at keeping the supply in tune with demand; they sell more knives, and flippers would learn a lesson.
(even if it turned into a future-order-list ... that pressure would lower the instant flippers profit margins and they'd be discouraged)
Sadly, custom hand makers can't really do this in a practical way, time is time, and it's not practical to 'hire help' to make it happen.
...
The fact that spyderco (& others) COULD EASILY do this for 'sprint' runs and they don't, really turns me off of trying to buy any of their sprint runs, which really turned out to be a blessing in a way, forcing me to expand my horizons. I found much better value from other vendors/mfgs as a result.