A deck can have any number of cards named Slime Against Humanity.
So the math only works at the top of the value range
A BGS 9.5 of this Shadowless version Charizard sold in the range of $3,500-8500 at eBay auction this month
However, just the ability to make creature tokens can be worth it in the right deck -- and in particular, that deck will be the UW one, which will be able to run a bunch of enchantments in the form of disturb creatures, and thats also the color pair that will have the most spirits
With Sigarda out, that no longer becomes an option, reducing your opponents to board wipes of some kind, which arent always great in many scenarios
While the buff is nice and synergizes well with many strategies, this card's charm rests in the final mode that allows you to draw a few cards