Right now on Amazon, you can score OshKosh B’Gosh Kids’ Flip-Flops for only $4.80! Sizes range from toddler 2/3 all the way to 13/1 kids. There are many fun colors to choose from for both boys and girls. Up to size 10 has a back strap to keep the flip flop on.
Note: These have a 3 star review, but most of the complaints are that the larger sizes did not have a back strap. This is as described in the description where only up to size 10 has the back strap.