Cheapest priced copy (The Brothers' War): $0.49 at Card Kingdom, near mint, their price list as of .
Urza's Command 
Instant · Rare · The Brothers' War · #318
Choose two —
• Creatures you don't control get -2/-0 until end of turn.
• Create a tapped Powerstone token.
• Create a tapped 0/0 colorless Construct artifact creature token with "This token gets +1/+1 for each artifact you control."
• Scry 1, then draw a card.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Brothers' War | 70 | Rare | $0.49 | $0.49 |
| The Brothers' War | 318 | Rare | $0.59 | $0.79 |
| The Brothers' War Promos | 70p | Rare | $0.49 | $0.79 |
| The Brothers' War Promos | 70s | Rare | — | $0.79 |
4 rulings from Wizards of the Coast
- 14 October 2022The ability of that Construct token does count the Construct itself, so it'll be at least 1/1.
- 14 October 2022You can use the {C} added by a Powerstone token on anything that isn't a nonartifact spell. This includes paying costs to activate abilities of both artifact and nonartifact permanents, paying ward costs, and so on.
- 14 October 2022Powerstone tokens are a kind of predefined token. Each one has the artifact subtype "Powerstone" and the ability "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell."
- 14 October 2022Although all the cards in The Brothers' War that create Powerstone tokens create a tapped Powerstone token, entering the battlefield tapped isn't part of the token's definition. Notably, if you create a token that is a copy of a Powerstone token, the token copy won't enter the battlefield tapped.