Why? Well, the plushie was only sold at an exclusive Touhou event last week, and it's “Jumbo Suika (eyes closed version),” so it's a big plushie (see in the picture, she takes up a good chunk of that chair). That might explain why the starting price was ¥12,000 ($124ish USD). No, the real key point is that only ten of this plushie were made.
One of the exhibitors said that it seemed sad that someone who only wanted to resell the item was able to get it. On the other hand, now someone who wanted it bad enough to pay over nine grand for it got it, so I guess it's not SO sad.
not for the same reason, anyway. (Via 2ch.)