Like most Magic: The Gathering cards, the value of Sol Ring depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Fallout)
Once you've scried, Elminster is adept at allowing you to make the most out of the cards you've placed atop your library
Perilous Snare Artifact removal is severely underutilized in most formats, allowing Perilous Snare to function as a semi-permanent removal option
I have a Will the Wise and Mike, the Dungeon Master deck (or Wernog, Riders Chaplain and Othelm, Sigardian Outcast deck, if youre nasty)
Not all cards are meant to be played with
Additionally, while The Queen's Castle only costs four ink to play, it will give two lore and has a defensive willpower of seven