Did I need to buy 3 of these for my kids? Could I have found cheaper costumes? No, and yes. BUT, let's just have a candid moment of absolute honesty. This was seriously the very best and most fun I have EVER had as an adult on Halloween. My kids love dinosaurs, and they were thrilled with these costumes. They were relatively easy to get on and off, quite warm for our cold Halloween, and a major hit with friends, family, and neighbors! No joke, they got extra candy at almost every house just because they made people laugh. My husband and I wore the adult costumes, and it was hilarious. My kids still enjoy wearing these around the house, having battles, sliding all over the floor, and general hilarity ensues.
For sizing- the costumes were big on my 3 year old, perfect for my 5 year old, and ALMOST starting to be too small for my gigantic almost 8 year old. They are very forgiving because of the way they're made, so they can accommodate a variety of sizes. If my kids weren't stair stepped in size and age like they are, I might've ordered an adult costume for biggest boy. It worked fine though, honestly.
My only recommendation is to bring backup batteries if you plan on wearing them for awhile, or put fresh batteries right before you go, but they last a few hours.