It must be a bit of a conundrum for the dealer as pinball buyers are most definitely used to being able to play a machine prior to purchase so they do need to have demo machines. Yet for a NIB machine, as soon as it is played it must lose around $500 - $1000 I guess?
I assume they take a hit on the opened machines and write that off as a marketing cost or similar - and sell enough NIB machines to make it worth their while.