Cheapest priced copy (Gatecrash): $0.35 at Card Kingdom, near mint, their price list as of .
Forced Adaptation 
Enchantment — Aura · Common · Gatecrash · #120
Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Gatecrash | 120 | Common | $0.35 | $0.99 |
| Ravnica Remastered | 140 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 24 January 2013The creature that gets the +1/+1 counter is the creature enchanted by Forced Adaptation when the ability resolves.
- 24 January 2013If Forced Adaptation’s ability triggers but Forced Adaptation isn’t on the battlefield when the ability resolves, put a +1/+1 counter on the creature it was enchanting when it left the battlefield.