Cheapest priced copy (Core Set 2020): $0.35 at Card Kingdom, near mint, their price list as of .
Growth Cycle 
Instant · Common · Core Set 2020 · #175
Target creature gets +3/+3 until end of turn. It gets an additional +2/+2 until end of turn for each card named Growth Cycle in your graveyard.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2020 | 175 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 12 July 2019Because Growth Cycle is still on the stack as you perform its instructions, it isn’t in your graveyard and won’t add to the bonus the creature gets.
- 12 July 2019The size of the bonus is determined as Growth Cycle begins to resolve; it won’t change later in the turn if the number of Growth Cycles in your graveyard changes.