Prices will go up in 10 years time. Maybe 10% on DMDs or slightly higher. High End restores are already in huge demand. SS will increase by more than DMDs. Part of this reason is the license that SS games hold. Playboy is a classic example. You could buy them for $600 in the 90's, they are now worth $3000 for a poor example. When Hugh finally kicks the bucket, they will double in price. Proof of this was the Evel Knievel Pin. Before he died, it was a $2000 pinball. Post death - $3500. Stern Ali is worth $1800. When he passes - $3000. This can't be said of DMDs. Scared Stiff won't increase by 30% when Elvira passes.

EMs are already increasing in demand and pricing.

DMDs have dropped slightly due to the standard of games supplied to the market at the moment.

The "big picture" - ALL machines will increase by at lease 10%, but the biggest mover in 20 years time will be licensed SS games, followed by Star Treks and Star Wars titles.