Cheapest priced copy (Khans of Tarkir): $0.49 at Card Kingdom, near mint, their price list as of .
Mindswipe 
Instant · Rare · Khans of Tarkir · #189
Counter target spell unless its controller pays {X}. Mindswipe deals X damage to that spell's controller.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Khans of Tarkir | 189 | Rare | $0.49 | $1.49 |
2 rulings from Wizards of the Coast
- 20 September 2014If the controller of the target spell pays {X}, the spell won’t be countered. Mindswipe will still deal damage to that player.
- 20 September 2014If the target spell is an illegal target as Mindswipe tries to resolve (perhaps because it was countered by another spell or ability), Mindswipe won’t resolve and none of its effects will happen. No damage will be dealt.