I got a toddler sized poncho at Eckerd, (where I work). It is made by Fisher Price and features the Little People. It comes in it's own case, the poncho has a zipper pocket in front, and they come in blue and pink. It was a little pricey- around $6.00 but it is heavy duty nylon and can be worn many time. Also I just remembered, it had this neat feature- it has Velcro under the arms so you can create armholes and anchor to you child a little more securely.
Hope this helps,
Sherrie