This came from a pack, however, making it part of the D/P set, and not a tin, which are classified as Black Star Promos. Logically, non-tin Lv. X's should be worth a lot more than tin Lv. X's, even if they already have a tin counterpart. I wouldn't know, however, since I've lost track of card prices long ago. (Is Pojo still around? back in the early days of Pokémon, I used that site to find card values all the time.)
From what I've seen, the only reason why in-game worth of a card would be related to monetary worth is in cases where they become archetypes or staples, such as Holon's Castform, Versatile Mew ex, Claydol, and Gardevoir Lv. X. The reason for that is because players buy most of them up, leaving few left for the collectors and thus driving up their prices. Torterra Lv. X would probably cost no more than Electivire Lv. X or Lucario Lv. X but would still be worth a lot more than a holographic Rare.