A friend of mine contacted the seller of that listing a while ago, and the seller confirmed for him that the card was sold for the listed price. With Neve being a sought-after promo that was released in only a few countries with a limited quantity, I am not surprised either that it sold for that price. Especially so with the recent increased interest in trading cards.
äksä is correct about the collectors from Japan being willing to pay a lot for certain TCG cards. I recently saw someone value a Spanish Bolmeteus at 5k €. There's a good chance that the buyer of Neve was from Japan.
The Scream Slicer promo is incredibly rare, so zero luck at finding one is the norm. It took me years of intense and daily searching before I found mine. And even then luck had some part in me finding it. This is the one card which stops people from completing their English collection, as they were only produced in the US, before being instantly recalled and destroyed. A few made it out, possibly through WoTC employees who kept some. Only two were sold through Troll&Toad, and for all we know that could be all there is.
There was a lead on a Scream Slicer promo on the Pojo.biz forums, but it turned out to be a dead end, since the owner of the card hasn't been online since 2013. He also quit Duel Masters and was selling his cards. So it may be that pojo was the forum you saw it on. Another site I could think of is the WoTC Duel Masters forums. Sadly, the latter hasn't been saved by anyone in waybackmachine.