Cheapest priced copy (Core Set 2019): $0.35 at Card Kingdom, near mint, their price list as of .
Skyrider Patrol 
Creature — Elf Scout · 2/3 · Uncommon · Core Set 2019 · #224
Flying
At the beginning of combat on your turn, you may pay {G}{U}. When you do, put a +1/+1 counter on another target creature you control, and that creature gains flying until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2019 | 224 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 13 July 2018Skyrider Patrol’s triggered ability goes on the stack without a target. While that ability is resolving, you may pay {G}{U}. If you do, a second ability triggers and you pick a target creature. This is different from abilities that say “If you do . . .” in that players may cast spells and activate abilities after mana is paid but before the target receives a counter and flying.
- 13 July 2018While resolving the triggered ability of Skyrider Patrol, you can’t pay {G}{U} multiple times to give more than one +1/+1 counter.