Cheapest priced copy (Double Masters 2022): $0.35 at Card Kingdom, near mint, their price list as of .
Knightly Valor 
Enchantment — Aura · Uncommon · Core Set 2019 · #20
Enchant creature
When this Aura enters, create a 2/2 white Knight creature token with vigilance. (Attacking doesn't cause it to tap.)
Enchanted creature gets +2/+2 and has vigilance.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
7 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters 2022 | 14 | Common | $0.35 | $0.49 |
| Jumpstart | 115 | Common | $0.35 | — |
| Core Set 2019 | 20 | Uncommon | $0.35 | $0.49 |
| Magic Origins | 22 | Uncommon | $0.35 | $0.49 |
| The List | RTR-13 | Common | $0.35 | — |
| Return to Ravnica | 13 | Common | $0.35 | $0.49 |
| Wilds of Eldraine: Enchanting Tales | 8 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 13 July 2018If the creature this Aura would enchant is an illegal target by the time Knightly Valor tries to resolve, the Aura spell doesn't resolve. It won't enter the battlefield, so its ability won't trigger.
- 13 July 2018You need a creature for Knightly Valor to target as you cast it. There's no way to have it enter the battlefield attached to the Knight token it'll create.