It's worth saying plainly: Mega Delphox ex is a playable Standard card, not only a collectible. Because every rarity of the same card shares identical rules text, the Double Rare print is functionally everything a competitive player needs — there's no reason to pay collector prices for a copy you intend to shuffle into sixty cards and sleeve for a tournament. A lot of the search volume around #008 comes from exactly that: people filling out a decklist, not people chasing an art slot.
The character helps here too. Delphox has carried a dedicated fanbase since the Fennekin line debuted in the XY era, and its first Mega form gives that group a genuine reason to care beyond nostalgia — a fire-type Mega Pokémon slots naturally into fire-leaning Standard builds released alongside Pitch Black. If you're weighing #008 against the set's pricier prints for an actual deck rather than a binder, our Pitch Black set guide breaks down where it fits next to the set's headline attacker, Mega Darkrai ex.
This is also the practical reason Swaptio's catalog treats every rarity of a card as the same underlying Pokémon with different prints, rather than as unrelated listings: whether a trade partner offers you the Double Rare, the Illustration Rare, or the Hyper Rare version of Mega Delphox ex, you're evaluating the same deck slot, just at very different price points.