Cheapest priced copy (Khans of Tarkir): $0.35 at Card Kingdom, near mint, their price list as of .
Briber's Purse 
Artifact · Uncommon · Khans of Tarkir · #217
This artifact enters with X gem counters on it.
{1}, {T}, Remove a gem counter from this artifact: Target creature can't attack or block this turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Khans of Tarkir | 217 | Uncommon | $0.35 | $0.49 |
| Ugin's Fate | 217 | Uncommon | $0.35 | — |
2 rulings from Wizards of the Coast
- 20 September 2014If Briber’s Purse has no gem counters on it, it remains on the battlefield, although you can’t activate its last ability.
- 20 September 2014Activating the ability targeting a creature that’s already attacking or blocking won’t remove it from combat or affect that attack or block.