Cheapest priced copy (Shards of Alara): $0.35 at Card Kingdom, near mint, their price list as of .
Sphinx's Herald 
Artifact Creature — Vedalken Wizard · 1/1 · Uncommon · Shards of Alara · #58
{2}{U}, {T}, Sacrifice a white creature, a blue creature, and a black creature: Search your library for a card named Sphinx Sovereign, put it onto the battlefield, then shuffle.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shards of Alara | 58 | Uncommon | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 1 October 2008To activate the ability, you must sacrifice three different creatures. You can’t sacrifice just one three-colored creature, for example.
- 1 October 2008You may sacrifice the Herald itself to help pay for the cost of its ability.
- 1 October 2008You may sacrifice multicolored creatures as part of the cost of the search ability. If you sacrifice a multicolored creature this way, specify which part of the cost that creature is satisfying.
- 1 October 2008The only difference between a colored artifact and a colorless artifact is, obviously, its color. Unlike most artifacts, a colored artifact requires colored mana to cast. Also unlike most artifacts, a colored artifact has a color in all zones. It will interact with cards that care about color. Other than that, a colored artifact behaves just like any other artifact. It will interact as normal with any card that cares about artifacts, such as Shatter or Arcbound Ravager.