Just adding in case anyone's looking for this (as I am, now): I found a 12x16 pillow at USA Baby for $10 and a 12x16 travel pillow at Linens N Things for $9. Linens N Things also has a white pillowcase (closes with a zipper). I don't know if the pillows are too puffy though; the USA Baby one seemed slightly flatter, and I haven't yet tried mine out with my daughter.
The products at Mr Bobbles Blankets (online) look really cute too though!
Ruth