If so, why not an AR as it has an adjustable stock and could grow with him (physically and technically) as he gets older
Jeremy, I don't know. Price didn't really factor into it, but I'm not getting him a Heym. More concerned with an optimal choice than a price point. However, I'm still not getting him a Heym.
I believe you can hunt (deer) with a .223 there (when I was young it was .23 or bigger, but now the regs just say centerfire), but the deer there are big like here. Not certain if .223 is an optimal choice.
Self-loaders are a no-no in Pennsylvania (unless you have lost an arm and my nephew has both).
You could convert your AR to a single shot and be legal in PA but his father and I prefer the bolt-action weapon.
Savage makes a really nice combo in .243, complete with scope and their Accutrigger, for a decent price. In our store, they are about $600. Liable to be able to find them a little cheaper with some shopping.
The scope is adequate, the rifles are very accurate, and I cannot sing the praises of the Accutrigger highly enough. Just another option to consider.