I ended up ordering from here
They were only $15 each even with all the engraving. I figured if they really start to wear them when they're worn out I can get them more expensive ones.
These don't need a size because they're adjustable. The twill tape is soft against the skin and they come in cute patterns so your kid could pick one out and maybe make them more inclined to wear it.
To my boys: I will love you for you Not for what you have done or what you will become I will love you for you I will give you the love The love that you never knew