I saw them on cafepress and etsy We don't have a large selection of maternity stores around though, so I didn't look in too many places besides online.
I ordered one through etsy, but then my friend who was pregnant last halloween gave me hers as well. It was a motherhood maternity one. Maybe they have them in the stores?
I'm plus size so I bought the iron on transfer and used a big black maternity shirt. I think it turned out pretty well, but one of the toes appears to have stuck onto the transfer sheet...
Re: Skeleton shirt