Yeah I did buy it in the KG lot recently listed on Ebay; but in my opinion got it for a good price. (US$82.50 if anyone is wondering).
Of these "BLACK" Die Cuts I have only seen 2 listed for bidding and 2 for buy it now. The 2 for bidding were Elton Brand (sold for well in excess of US$100) and Ben Wallace (who from memory sold for US$95 or so). The 2 buy it now were both LeBron's; the first was listed for US$750 and the second is currently listed for US$1200. And then you have 2 listed on the Beckett website; Darko for US$75 & Sweetney for US$45 (2 hacks that don't even deserve their faces on these cards).
Going by all this I would have to think KG was close to the US$200 mark; his popularity has risen in the past 6 months (and still going up) and being that these are very scarce and that they are in an 03/04 product only gives them more value..