Cheapest priced copy (Scars of Mirrodin): $2.49 at Card Kingdom, near mint, their price list as of .
Myr Reservoir 
Artifact · Rare · Scars of Mirrodin · #183
{T}: Add {C}{C}. Spend this mana only to cast Myr spells or activate abilities of Myr.
{3}, {T}: Return target Myr card from your graveyard to your hand.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $2.49 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Scars of Mirrodin | 183 | Rare | $2.49 | $3.49 |
3 rulings from Wizards of the Coast
- 1 January 2011A card, spell, or permanent is a Myr only if it has the subtype Myr, regardless of its name. For example, Myr Reservoir itself is not a Myr.
- 1 January 2011You can use the mana produced by Myr Reservoir’s first ability to pay an alternative cost or additional cost incurred while casting a Myr spell. It’s not limited to just that spell’s mana cost.
- 1 January 2011The mana can’t be spent to activate activated abilities of Myr sources that aren’t on the battlefield.