Cheapest priced copy (Tempest): $0.49 at Card Kingdom, near mint, their price list as of .
Echo Chamber 
Artifact · Rare · Tempest · #282
{4}, {T}: An opponent chooses target creature they control. Create a token that's a copy of that creature. That token gains haste until end of turn. Exile the token at the beginning of the next end step. Activate only as a sorcery.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Tempest | 282 | Rare | $0.49 | — |
2 rulings from Wizards of the Coast
- 4 October 2004The token enters as the creature it is copying. This triggers its own and any other appropriate "enters" abilities.
- 1 April 2008The effect only grants Haste until the end of the current turn. If the creature somehow manages to stick around until a later turn, it will no longer have Haste.