Amazon has Kids Batman Rain Coat with Cape for a geektastic $44.99 plus free shipping. Sales tax applies in KS, KT, NY, ND, WA. This deal beats the next best price by $8. Sold by Little Folks.
Superhero rain coat features glow-in-the-dark Batman logo and detachable cape which can be worn separately. Removing the cape also makes it easier to wash but I know you’re more likely to wear the cape even on sunny days. Comes in sizes from 2T to 6X.