Cheapest priced copy (The Lost Caverns of Ixalan Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Fathom Fleet Captain 
Creature — Human Pirate · 2/1 · Rare · Ixalan · #106
Menace
Whenever this creature attacks, if you control another nontoken Pirate, you may pay {2}. If you do, create a 2/2 black Pirate creature token with menace.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $5.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan Commander | 197 | Rare | $0.49 | — |
| Ixalan Promos | 106p | Rare | $5.49 | $4.99 |
| Ixalan Promos | 106s | Rare | — | $2.49 |
| Ixalan | 106 | Rare | $0.49 | $0.49 |
2 rulings from Wizards of the Coast
- 29 September 2017If you don't control another nontoken Pirate at the moment Fathom Fleet Captain attacks, its triggered ability won't trigger. If you don't control another nontoken Pirate as that ability resolves, you can't pay {2}.
- 29 September 2017While resolving Fathom Fleet Captain's triggered ability, you can't pay {2} multiple times to create more than one Pirate token.