Prices go up because of the short supply of this specific card
(Mana value typically doesn't change, but your commander may become a copy of something else.) The Germ token enters the battlefield as a 0/0 creature and the Equipment becomes attached to it before state-based actions would cause the token to die
X must pay a fairly hefty 2 Energy to retreat
While other popular sets might have one or two valuable cards, Prismatic Evolutions currently has more than 15 chase cards, all worth over 100 dollars
Slap this in my Lyzolda, the Blood Witch or Thalisse, Reverent Medium or even my new The Ever-Changing Dane lists, and the Weatherlight Compleated will be a creature in no time, scrying you to more ways to have your creatures die
That said, there are plenty of amazing spells in this deck to compensate for some of the weaker parts