Cheapest priced copy (Bloomburrow Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Chatterstorm 
Sorcery · Common · The Zeta Set · #193
Create a 1/1 green Squirrel creature token.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)
Legal inCommanderModernLegacyVintage
Banned inPauper
Not legal inBrawlStandardPioneer
6 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Bloomburrow Commander | 210 | Common | $0.35 | — |
| Modern Horizons 2 | 152 | Common | $0.35 | $0.49 |
| Modern Horizons 2 | 411 | Common | $0.35 | $0.49 |
| The Zeta Set | 72 | Common | — | — |
| The Zeta Set | 193 | Common | — | — |
| The Zeta Set | 314 | Common | — | — |
5 rulings from Wizards of the Coast
- 18 June 2021 If a spell with storm has targets, you may choose new targets for any of the copies. You can make different choices for each copy.
- 18 June 2021 The copies are put directly onto the stack. They aren't cast and won't be counted by other spells with storm cast later in the turn.
- 18 June 2021 A copy of a spell can be countered like any other spell, but it must be countered individually. Countering a spell with storm won't affect the copies.
- 18 June 2021 Spells cast from zones other than a player's hand and spells that were countered or otherwise failed to resolve are counted by the storm ability.
- 18 June 2021 The triggered ability that creates the copies can itself be countered by anything that can counter a triggered ability. If it is countered, no copies will be put onto the stack.