To determine the best Simic cards, I look for efficiency first and foremost the most impact you can have for the least mana
Kaust, Eyes of the Glade and Yarus, Roar of the Gods can both thrive with a creature like Aschloud Phoenix, as both of them can draw you cards with face-down creatures and turn creatures face up for free
Ive had both of these cards in my book for months, and Ive had interest from ten or fifteen people
While Charizard dominates the market, other iconic characters like Mew and Blastoise EX also maintain strong collector interest, though rarely matching Charizard's premium
I almost dropped the "budget" aspect from the title because of this
That also pushes it towards good stuff soup, but many 5-color commanders suffer from that