Cheapest priced copy (Duel Decks: Nissa vs. Ob Nixilis): $0.35 at Card Kingdom, near mint, their price list as of .
Jaddi Lifestrider 
Creature — Elemental · 2/8 · Uncommon · Rise of the Eldrazi · #189
When this creature enters, you may tap any number of untapped creatures you control. You gain 2 life for each creature tapped this way.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Nissa vs. Ob Nixilis | 12 | Uncommon | $0.35 | — |
| Rise of the Eldrazi | 189 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 15 June 2010You don’t choose which creatures to tap until the ability resolves. You may tap Jaddi Lifestrider itself this way, assuming it’s still on the battlefield untapped by this time.