Cheapest priced copy (Dominaria United): $0.35 at Card Kingdom, near mint, their price list as of .
Micromancer 
Creature — Human Wizard · 3/3 · Uncommon · Foundations · #158
When this creature enters, you may search your library for an instant or sorcery card with mana value 1, reveal it, put it into your hand, then shuffle.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria United | 57 | Uncommon | $0.35 | $0.49 |
| Dominaria United | 431 | Uncommon | $0.35 | $0.49 |
| Foundations | 158 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 9 September 2022If a card in a player's library has {X} in its mana cost, X is considered to be 0.