Cheapest priced copy (Planar Chaos): $0.35 at Card Kingdom, near mint, their price list as of .
Gossamer Phantasm 
Creature — Illusion · 2/1 · Common · Planar Chaos · #55
Flying
When this creature becomes the target of a spell or ability, sacrifice it.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Planar Chaos | 55 | Common | $0.35 | $0.49 |
| Time Spiral Remastered | 70 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 19 March 2021If the spell that targets Gossamer Phantasm has no other targets, it won't resolve (because it no longer has a legal target after Gossamer Phantasm has been sacrificed).
- 19 March 2021Gossamer Phantasm's triggered ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.