Can you link to the one for $900 or was it not online ?
Would have to be a fairly significant maker to achieve that type of price at auction. One by Deakin sold for £1,100 but it was a large, very fine dressing table mirror.
The type you have is usually more low hundreds.
Also, like i said earlier, i'd expect that registration mark to throw up more Google results than it does. Vast majority refer to that one seller.