http://search.ebay.com/251105620795
 Hardly Apple I territory, but 1,100.00 GBP (~ 1700 USD) is an incredible  
 
_How much_?
I've got 3 or 4 of them. I've also got the official Econet interface
(fits on the track side of the main PCB) in one of them. A couple of the
others have 'System' eurocard I/O bords fitted inside the case (the Atom
expansion connector is essentially the System bus).
It's odd what people will pay serious money for...
  amount for a home computer which occupied the middle
ground: not as
 ubiquitous or famous as the Spectrum, C64, BBC micro etc., but not as rare
 or desirable as those which came before it (ZX80, Acorn System 1 etc.)
 It's not as though it's an early release or one of the ones sold in kit
 form. The lack of serial number on the case raises the possibility that the
 case and PCB weren't paired at the factory (which surely makes it
 non-original and a mongrel :-) 
What happened if you bought it as a kit? Was there a serial number label
included in the kit? Perhaps it was never stuck on.
-tony