As a direct point of comparison, this exact Marnie card appears in English's Sword & Shield Base Set, but only commands a fraction of her Japanese value, settling at around $30
Commander Spellbook is exclusively a database for combos (usually ones that can generate infinite mana or cards) in the Commander format
Here are the top 30 most expensive cards that can be found in Outlaws of Thunder Junction , including OTJ's Commander precons (OTC), The Big Score set (BIG), the Breaking News/Crimes bonus sheet (OTP), and the Special Guest (SPG) slot
Neheb, the Eternal looks like it finishes games in fireworks, and it can indeed do that
If you dont collect master sets, or you find yourself with dozens of duplicate cards, the next thing youre doing is trying to figure out how to get rid of all of it while getting back a fraction of what you paid for it in return