I sometimes consider very early 90's games as 80's games--one thing they did not have today's DMD screens they used Alpha numeric scoring.
Back to the Future was designed in the year 1990.
Elvira and the party Monsters--1989--- any pin can sell for 3 grand most are flukes or it could of been one of Elvira's personal pins/autographed. they are tough to sell--- Scared Stiff, different story
Funhouse-- again, designed in 1990-- this game routinely sells in the 2 grand price range in good shape-- Not a Fluke; Cyclone will go for a lot cheaper.
Haunted House--1982-- nice game-- sells usually in the 1,000 -- 2,000 in real nice shape but you can find working ones sometimes for under a 1,000 without difficulty.
Rocky--Rare pin, a true Ultra collector pin, not a good game by any means but price commands its Rarity / and Rocky Theme... but $5,000 I would have to question someone's common sense.... Now a KRULL that would be totally a different story.
Eight Ball Deluxe / Fathom......

? you will always find outliners.... hell last year someone was willing to Pony up $13,000 for a Cactus Canyon, He overpaid by at least $5,000.
To each his own, it is a "Buyers Market" for pins. They are still selling though, I have bought 4 this year alone (late 1990's era) and have sold 3, and will be putting up my Lord of the Rings in the next few days probably to get a Pirates of the Caribean. Nice Pin, needs some better programming(Code) but the plafield is laid out nice, and the outlane posts need to be moved out to make it more difficult.
I would offer, $1,000 for that back to the future-- and only if, you like the pin a lot.
Scott
Detroit