One card, the Buy-a-Box card, only exists in its Godzilla Series form, but each of the others has both an Ikoria card and a matching Godzilla Series card
I could maybe see this one getting included in some D&T lists depending on how the meta shakes out, since this is good against Snapcaster type effects (even then, it seems like a stretch)
Skullclamp is broken because it can do both and the opportunity cost for doing so is just play creatures with one toughness alongside some sort of mana engine. Thats it
Since it's an instant, you simply pass your turn, wait until your opponent's upkeep, and then cast it, which is very close to getting an extra turn (the main difference is that your opponent will get to untap)
A random eBay seller is presumably more difficult to track down
However, cards worth more than $0.25 are usually listed at $0.10-0.15 or higher