Cheapest priced copy (Eldritch Moon): $0.35 at Card Kingdom, near mint, their price list as of .
Thirsting Axe 
Artifact — Equipment · Uncommon · Eldritch Moon · #202
Equipped creature gets +4/+0.
At the beginning of your end step, if equipped creature didn't deal combat damage to a creature this turn, sacrifice it.
Equip {2}
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Eldritch Moon | 202 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 13 July 2016If the equipped creature dealt combat damage only to a player or planeswalker, Thirsting Axe’s triggered ability triggers. The same is true if the creature didn’t deal combat damage at all.
- 13 July 2016Thirsting Axe’s triggered ability checks whether the creature it’s attached to at the moment your end step begins dealt combat damage to a creature earlier in the turn. It doesn’t matter whether Thirsting Axe was attached to it (or to any creature at all) as combat damage was dealt.