If I remember correctly, these were available from the Pokemon Center stores that were on the 10th Anniversary tour, as well as the New York center way back when.
I have several different ones, including 2 of the Skitty.
Collectively at every tournament I went to from 2004 through 2009, on ebay, in resale shops, at Disney World who had 10 cases of twenty each plus what they had on the shelf, online stores, etc.
lol
Actually, too lazy to take a pic of mine, but the one I have is still in nm condition anyways. Left it on a top shelf and never touched since.
But, looks like a keep as might not get much for it anyways.
Well, I was just looking at eBay and they have several of the different pillows listed anywhere from $24.95 BIN to $94.95 BIN depending on the character on the pillow.