Why is Grim Tutor worth 10x the cost of a Demonic Tutor, a card that's better in every way?
Supply. Grim Tutor was only printed in paper in Starter 1999, so there is a very small supply of it. And quite a few decks that want one tutor (like the best Demonic Tutor) want all the tutors in order to increase consistency. So if you're building a very competitive EDH deck, and you want all the available tutors in order to tutor out your combo, this card can be in demand.
Supply. Grim Tutor was only printed in paper in Starter 1999, so there is a very small supply of it. And quite a few decks that want one tutor (like the best Demonic Tutor) want all the tutors in order to increase consistency. So if you're building a very competitive EDH deck, and you want all the available tutors in order to tutor out your combo, this card can be in demand.
Currently Playing:
Multiplayer EDH Lists (click italics for a link to the thread!)
[Primer] Lord of Tresserhorn - Don't Tell Me What I Can't Do[Primer] Roon of the Hidden Realm - Rhino Blink
5 Color Tribal Guide (Slivers, Atogs, Allies, Spirits)
Also Playing (most decklists can be found on my profile)
MarathGeistKamahlGrenzoBolasThassaGitrog
PiratesZurVial Smasher&ThrasiosYennettJhoira(cEDH)Strix(Pauper)
Legacy: Maverick
Modern:
Melira PodRIP 1/19/15GWHatebears