Thanks, everyone. I finally caught someone at home but it turns out they don't own the dish (I got the impression it's either a rental house or owned by a relative) and the owner lives quite some distance away. Even so they made it sound like he probably would not want to part with it, at least not without being paid some serious cash, otherwise he'd prefer to scrap it. It never ceases to amaze me how many people have dishes like this that think they are going to make a windfall if they take them to the scrap yard, and who are under the impression that the dish is solid aluminum (then when you don't bite the dish still just sits in their yard, because they will never be motivated enough to actually take it to the scrap yard). I don't know about other areas but I do know that with the scrap yard in our area, if an item is not PURE aluminum (with not even so much as a steel sheet metal screw in it) they will call it "mixed metals" and you would be lucky to get ten bucks for an item that size, which would barely cover your gasoline to get it there. I haven't completely given up on it, but I'm a lot less optimistic than I was.
(The scrap yards are ripoff artists in their own right, if I could get a pole like the one on that dish down they MIGHT give me two bucks for it if I sledgehammered all the concrete off first, but last time I went to buy a couple they charged me $15 apiece for a couple very rusty 8 foot pipes. I think if you have spare property and don't mind getting dirty, scrap is the business to be in!)