Quoted from dmklunk:These are worth more than the subsequent machines for a few reasons. Partially because they have the diamond plate playfields which obviously don't wear as much as the subsequently produced playfields, ironically. In general, a prototype is worth more. But being that this specific prototype has the Diamond Plate playfields that the subsequent machines lacked, makes it worth more.
That's true, assuming the playfield isn't blown out, anyway. I mean DP playfields are great, but they can still get abused on location and worn beyond useful repair, anyway.
But in general you are correct...when two machines are similar in condition, the sample will be worth more than a regular production. And a true prototype even more.
--Donnie