When this 1st came out, it sold for about $60 for the 15 YO. Then they released an NAS version and 2nd batch of 15 YO. The NAS is around $40 but the 15 had big price increase and now $130-$150. You might still find stray bottles of 1st batch for $60. Other than price, I don't think there is anyway to tell what batch is what.
I bought a couple at the $60 price point and thought is was pretty good at that price point. For $140 no way.