But then, this is all based on the assumption that you buy a brand new set. I for one would not give a pre-teen child a high tech expensive toy. Yes, $150 or so is rather expensive in my book for a kid's toy. I would either search out nice individual postwar or MPC era pieces and build a set or look for a decent MPC era set to give a kid. Marx or early K-line stuff would also work.
If I was someone who didn't know trains looking for a set for my kid, one of the sub $100 HO sets would probably get my eye for a starter set. Which is what my folks bought me for my first train when I was 12 years old.