Cheapest priced copy (Commander 2020): $3.49 at Card Kingdom, near mint, their price list as of .
Knight of the White Orchid 
Creature — Human Knight · 2/2 · Rare · Commander 2020 · #93
First strike
When this creature enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
11 printings · $3.49 to $19.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shards of Alara | 16 | Rare | $4.99 | $19.99 |
| Commander 2020 | 93 | Rare | $3.49 | — |
| Commander 2021 | 95 | Rare | $3.49 | — |
| Duel Decks: Knights vs. Dragons | 6 | Rare | $3.99 | — |
| Midnight Hunt Commander | 88 | Rare | $3.49 | — |
| March of the Machine Commander | 193 | Rare | $3.49 | — |
| Magic Origins | 21 | Rare | $3.99 | $6.99 |
| Magic Origins Promos | 21s | Rare | — | $9.99 |
| Secret Lair Drop | 1045 | Rare | $14.99 | $11.99 |
| Secret Lair Drop | 7139 | Rare | — | $3.49 |
| Crimson Vow Commander | 92 | Rare | $3.49 | — |
2 rulings from Wizards of the Coast
- 1 October 2008Knight of the White Orchid's triggered ability has an “intervening ‘if' clause.” That means (1) the ability won't trigger at all unless any one of your opponents controls more lands than you, and (2) the ability will do nothing if you control at least as many lands as each of your opponents by the time it resolves.
- 22 June 2015The Plains you search for doesn't have to be basic. For example, you could put a Sacred Foundry onto the battlefield.