Please don't take the KIDS out with a Vest. As I'm sure you won't.
Sorry I can't give you exact places to shop.But I can tell you what you need to look for.
In no order.
1] high impact rate. example 50mph. should be on the inside tag.
2] a Skid collar a MUST!!!!!!!!!!!!
3]a grab handle attached to just behind the skid collar, so god forbid the child falls in the water.
you have something to extract them out with.