This is a very rare model, not often on sale and they often go for $1000+ so if a bezel and strap will only cost $40 to buy it's not a bad deal. Also it's unlikely to go down in value, it's not like anyone is about to discover a box of these and flood the market.
I'm with casiophile on this, in fact I think the price was towards the low end of the range. UK buyer, given the present currency valuations, probably thought he got a decent deal. These have gone much higher in the past. There was also a recent case, discussed on this forum, where the auction was inadequately described (fuzzy image, incomplete description, part of a group of junk watches) that closed at about US$200.
Here's another one, buyer was from Japan, seller probably set the BIN a little low:
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