suggestions for the little nephew...

I'm looking at getting a bass (maybe even a guitar) for my nephew. He's been through a few Target 30 dollar acoustics and he is nearly 5 years old. If it is 100 or 150, I don't mind. I even have an amp to hand off to him if it is a guitar, but the questions I have...

3/4 scale vs. a mini? For a 5 year old, what kind of scale should I be looking for? He's a few hours away and I'm unsure what he can hold in his lap or with a strap. Got any bass ideas?

He's a lefty when it comes to golf, he's a lefty when he writes, but... not always with the acoustic.