I dont think well ever see any of the big cracking operations pop up with a couple hundred copies of any Oil-Slick mythic, and once the current wave of bundles is gone, thats probably most of the inventory that will ever be available
One of Pokemon's biggest collab is that with Build-A-Bear Workshop
Because paying X is part of the normal casting cost, paying an alternative cost for these cards will result in X=0 unless the alternative cost itself specifies a value for X, such as Lantern Flare or Disrupting Shoal
(Although I did have a bunch of Shadowless cards) As you said, there may have been a select few places where this was an exception, but I think peoples view of just how common 1st ed Base cards are is heavily distorted because of the prominence of 1st ed Base in the high-end collecting world
7 Lutri, the Spellchaser Banned In Commander Due To Easy Companion Criteria The companion mechanic, which debuted in Ikoria, was quickly erratad due to its immense inherent power