I have one listed on Ebay...it's listed with some other items...unfortunately I think it might be xxs, let me check..... please see:
Lot 7 Hardly Used XXS Dog Shirt Sweater Dress Clothes - eBay (item 260360062485 end time Feb-16-09 15:25:04 PST)
It is an xxs, but it looks like an XS in real life. Unfortunately, since it's already posted, I can't separate it from the others, sorry....but I do have XS items for sale on Ebay too...thanks!