Leave him barefoot as long as possible, his bones haven't hardened yet.
Anything you get, make sure it has a soft sole, leather is fine, as you won't be letting him walk on stones for ages!

I did buy Pip some cute dunlop volleys from target but they were horrid, didn't last long or give him any support. His ankle rolled and the foot slid around inside the shoe.

If you're really wanting shoes, then go to a specialist kids' shoe shop, and get their advice. Buy the best quality you can afford