Cheapest priced copy (Duel Decks: Venser vs. Koth): $0.35 at Card Kingdom, near mint, their price list as of .
Primal Plasma 
Creature — Elemental Shapeshifter · */* · Common · Planar Chaos · #59
As this creature enters, it becomes your choice of a 3/3 creature, a 2/2 creature with flying, or a 1/6 creature with defender.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
5 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Venser vs. Koth | 16 | Common | $0.35 | — |
| Planechase 2012 | 23 | Common | $0.35 | — |
| Planechase Anthology | 23 | Common | $0.35 | — |
| Planar Chaos | 59 | Common | $0.35 | $0.49 |
| Time Spiral Remastered | 80 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 19 March 2021If an object enters the battlefield as a copy of Primal Plasma, it copies the values determined by its enters-the-battlefield replacement effect, but its power and toughness are determined by the copy's own enters-the-battlefield replacement effect. This can cause you to have a 3/3 creature with flying, or a 1/6 creature with flying and defender, for example.
- 19 March 2021If an object on the battlefield becomes a copy of Primal Plasma, it copies the values determined by its enters-the-battlefield replacement effect.
- 19 March 2021While not on the battlefield, Primal Plasma is a 0/0 creature card. It doesn't have flying or defender.