Maybe you can buy it from American Pool. Based on Pinball News they sold an AC/DC in the past.
http://www.pinballnews.com/sites/americanpool/
I was there three months ago. In general, their pinball machines were in O.K to good condition.
On the other hand, you can keep your eyes on local auction site such as
I bought two pinball machines from above auction site four years ago.
Good luck