I like the idea - if I were you (take this with a pinch of salt) just have a pinned post where you sell these.
then you've no real overhead if you find it impossible to part anyone from their BSV.
scale : if you made them Pokémon card shape less material cost, you could sell them in a Pokémon capsule/case for that extra shizzle
finish : your physical steel card print has a "anodised" finish whereas the ai image is a % more vivid, not telling you to go out and buy a UV printer but that would level up the finish, then you might use card stock which might defeat the whole point of it being out of your steel which I see is your wheelhouse .......
shipping : after a long hiatus I send a package recently from UK to US expecting it to be £12-15 it was nearly £30 it had tracking and was half the size of an apple. if you're not in UK and your package is friendly shape this might be a nothing burger..