Cheapest priced copy (Dominaria United): $0.49 at Card Kingdom, near mint, their price list as of .
Academy Loremaster 
Creature — Human Wizard · 2/3 · Rare · Dominaria United · #391
At the beginning of each player's draw step, that player may draw an additional card. If they do, spells they cast this turn cost {2} more to cast.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria United | 40 | Rare | $0.49 | $0.49 |
| Dominaria United | 391 | Rare | $0.49 | $0.49 |
| Dominaria United Promos | 40p | Rare | $0.49 | $0.99 |
| Dominaria United Promos | 40s | Rare | — | $0.99 |
2 rulings from Wizards of the Coast
- 9 September 2022The cost increase applies to spells that player casts even if they're casting them for an alternative cost. If they cast a spell without paying its mana cost, they'll still have to pay {2}.
- 9 September 2022Abilities that reduce the cost to cast a spell apply after abilities that raise them. For example, if an opponent chose to draw an additional card as Academy Loremaster's triggered ability resolved, Argivian Phalanx (a card with mana cost {5}{W} and the ability "This spell costs {1} less to cast for each creature you control.") will cost them {W} to cast that turn if they have seven or more creatures.