Cheapest priced copy (Jumpstart 2022): $0.35 at Card Kingdom, near mint, their price list as of .
Stalwart Valkyrie 
Creature — Angel Warrior · 3/2 · Common · Foundations Jumpstart · #258
You may pay {1}{W} and exile a creature card from your graveyard rather than pay this spell's mana cost.
Flying
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Jumpstart 2022 | 249 | Common | $0.35 | — |
| Foundations Jumpstart | 258 | Common | $0.35 | — |
| Kaldheim | 31 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 5 February 2021Stalwart Valkyrie has mana value 4, no matter what you actually paid to cast it.
- 5 February 2021Once you announce that you're casting Stalwart Valkyrie using its alternative cost, no player may take other actions until the spell's been paid for. Notably, players can't try to remove creature cards from your graveyard to stop you from casting the spell.
- 5 February 2021Casting Stalwart Valkyrie for its alternative cost doesn't change when you can cast it.