Quoted from CrazyLevi:
Swampwiz, here's a list of additional rare EMs that are worth a lot of money so you don't have to make a separate thread wondering if X is really worth X whenever you see one for sale. Due the rarity and/or art/gameplay, the following are likely worth X to somebody even if it seems super wacky!:
feel free to add to the list folks
Gottlieb woodrails Niagara, Spot Bowler, Queen of Hearts, Grand Slam, Bank-a-Ball and Daisy May belong on the list of EMs which continue to command a premium price, although peak prices for woodrails have softened somewhat in the last 2 years.
Gottlieb wedgeheads Blue Note/Rock Star are very low production games, which are great fun and which fetch top dollar. Wedgehead Hit-the-Deck (and Neptune to a lesser extent) has escalated in price over the past 5 years and continues on an upward vector.
Prewars have been hot in the last 3 years. The "aging collector " theory has limited merit, in my opinion. Current collectors never played a 1934/35 Rockola Army Navy on location, in their youth. Yet, restored examples of this game have sold for $15K -$23K in the past 6 years. This title sold for about $6K in 2007 and fetched about $3K in the late 1990s.
Likewise, 1933 Rockola Jigsaw continues to escalate each year in value.
The scarce games, which are fun, innovative and aesthetically appealing always have a respectable marketplace of enthusiastic buyers. Era of release, flipper size, "fast quotient" are, in my opinion, secondary factors which dictate price.