Another vote to offer $1800 and go up to $2100 since they've been sitting. Everything has to be gone through and that doesn't include parts you'll need which are extra. I agree too that you should get a volume discount - easier for the seller to move all at once.
Of the 3 Gottliebs Royal Flush and Team One are good games - I'd probably sell King Kool. Can't say about the others.