Cheapest priced copy (Lorwyn Eclipsed): $0.35 at Card Kingdom, near mint, their price list as of .
Goatnap 
Sorcery · Common · Modern Horizons · #126
Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. If that creature is a Goat, it also gets +3/+0 until end of turn.
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Lorwyn Eclipsed | 142 | Uncommon | $0.35 | $0.49 |
| Modern Horizons | 126 | Common | $0.35 | $0.49 |
6 rulings from Wizards of the Coast
- 14 June 2019To determine whether the target creature gets +3/+0, look at its creature types after you've gained control of it, untapped it, and given it haste. If it's not a Goat at this time, it won't get +3/+0, even if it becomes a Goat later in the turn. If it is a Goat, it gets +3/+0, even if it stops being a Goat later in the turn.
- 14 June 2019Goat is a creature type. You won't see this creature type printed on creatures in this set, but keep in mind that creatures with the changeling ability are Goats.
- 14 June 2019Goatnap can target any creature, even one that's untapped or one you already control.
- 17 November 2025Goatnap can target any creature, even one that's untapped or one you already control.
- 17 November 2025Goat is a creature type. Keep in mind that creatures with the changeling ability are Goats. (Whether they're "goated" or not is too subjective for this ruling to address.)
- 17 November 2025To determine whether the target creature gets +3/+0, look at its creature types after you've gained control of it, untapped it, and given it haste. If it's not a Goat at this time, it won't get +3/+0, even if it becomes a Goat later in the turn. If it is a Goat, it gets +3/+0, even if it stops being a Goat later in the turn.