Working pinballs (dmd's) like arcade games will always be worth as much money as they can make onsite when operated. They are a cheap thrill especially when money is tight. IMO $1400 for a working dmd is a good buy regardless of title & from experience I found some of the gottlieb the most reliable. 

Now - right there, is the biggest load of BOLLOCKS I have EVER read!!! Reliable and Gottlieb (when talking about SS machines) NEVER go in the same sentence!