Cheapest priced copy (Commander 2015): $0.49 at Card Kingdom, near mint, their price list as of .
Bonehoard 
Artifact — Equipment · Rare · Commander 2014 · #229
Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +X/+X, where X is the number of creature cards in all graveyards.
Equip {2}
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
8 printings · $0.49 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2014 | 229 | Rare | $0.69 | — |
| Commander 2015 | 245 | Rare | $0.49 | — |
| Commander 2016 | 245 | Rare | $0.59 | — |
| Commander Anthology | 211 | Rare | $0.59 | — |
| Mirrodin Besieged | 100 | Rare | $0.49 | $2.99 |
| Neon Dynasty Commander | 147 | Rare | $0.49 | — |
| The List | CMA-211 | Rare | $0.49 | — |
| Zendikar Rising Commander | 108 | Rare | $0.49 | — |
8 rulings from Wizards of the Coast
- 1 June 2011The value of X is calculated continuously as the number of creature cards in graveyards changes.
- 1 June 2011If lethal damage is dealt simultaneously to the equipped creature and another creature, both creatures are put into the graveyard at the same time. The equipped creature won't get an additional bonus from the other creature.
- 1 June 2011If there are no creature cards in any graveyard when Bonehoard's living weapon ability resolves, the Germ will be 0/0 and put into its owner's graveyard.
- 1 June 2011Although creature tokens go to the graveyard before ceasing to exist, they never count as creature cards and won't increase the bonus granted by Bonehoard, however briefly.
- 7 August 2020If the living weapon trigger causes two Germs to be created (due to an effect such as that of Doubling Season), the Equipment becomes attached to one of them. The other will be put into your graveyard and subsequently cease to exist, unless another effect raises its toughness above 0.
- 7 August 2020If the Germ token is destroyed, the Equipment remains on the battlefield as with any other Equipment.
- 7 August 2020The Germ token enters the battlefield as a 0/0 creature and the Equipment becomes attached to it before state-based actions would cause the token to die. Abilities that trigger as the token enters the battlefield see that a 0/0 creature entered the battlefield.
- 7 August 2020Like other Equipment, each Equipment with living weapon has an equip cost. You can pay this cost to attach an Equipment to another creature you control. Once the Germ token is no longer equipped, it will be put into your graveyard and subsequently cease to exist, unless another effect raises its toughness above 0.