Cheapest priced copy (Ninth Edition): $3.49 at Card Kingdom, near mint, their price list as of .
Storage Matrix 
Artifact · Rare · Ninth Edition · #310
As long as this artifact is untapped, each player chooses artifact, creature, or land during their untap step. That player can untap only permanents of the chosen type this step.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
3 printings · $3.49 to $69.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ninth Edition | 310 | Rare | $3.49 | — |
| Ninth Edition | 310★ | Rare | — | $24.99 |
| Urza's Destiny | 138 | Rare | $4.49 | $69.99 |
3 rulings from Wizards of the Coast
- 4 October 2004This card’s ability does not override effects which prevent a permanent from untapping.
- 1 August 2005Permanents with multiple types untap if any of their types is chosen. For example, an artifact creature untaps if either artifact or creature is chosen.
- 1 August 2005If another effect limits the number of permanents that untap, that number combines with Storage Matrix’s effect. For example, Imi Statue says “players can’t untap more than one artifact during their untap steps.” If both Imi Statue and an untapped Storage Matrix are on the battlefield, and you choose “artifact,” only one artifact untaps.