How are they getting so cheap?
Because you never know if they work. They just take the board layouts from the Arduino website and produce them as cheap as ever possible. If you have to get the included chips even in 1000s you pay more the $9 in normal situations.
But they never have to pay anyone for doing the engineering stuff, they just produce identical copies as cheap as possible. In some situations the chips are then fakes with just a copper plate in the plastic housing.
$69 is way too much though, I get them here in Switzerland for CHF 40 (~$45). Did you lookup the price for the shield with the PoE module? Your ebay clone doesn't include that module.