Today, Disney.com has their character sleepers for their deal of the day. They are priced at $6. It looks like they run from infant to 3T. Shipping is free if you spend $89 but it looks like you could order 4 sleepers and have shipping be just under $5.
Children's Place also has some winter sleepers on sale for $5.59, their sizes are getting limited. Shipping is always a $5 flat rate. There is a code for 15% off too, GGAC9.
Thanks common sense with money