The seller is is a known dealer in this sorta thing, especially printed matter.
I think what's happening here is that the seller might not have an idea what these should go for, or might only have a vague idea, so he's hoping to catch a good offer with the "or Best Offer" Ebay tab. You see it a lot with collectibles, you set the price high on the supposed rare and wanted item, and some goofball in a fit of lust offers you way more than market for it. Realistically, I'd figure it would go for $500 - 1000 if left as a stand alone auction.
I doubt anybody, minus Arnold could get anywhere close to that for a Sandow real or replica.
For instance, here is a site that deals in vintage awards from far more popular sports and many things are under even 1/2 the Sandow's asking price -
http://www.championship-rings.net/default.asp .