Buying a child a TT is not something I would do. It is like saying, "welcome to world of paranoia & misery".
I gave my eldest son a turntable when he was four. Crap plastic one but it cost me nothing. He was very careful with it and could use it fine. I think I replaced that with Systemdek 1, something like that, but his interest in turntables didn't last. He mostly listened to the radio then when my sister bought them all ipods it was game over.