Cheapest priced copy (Modern Horizons): $2.99 at Card Kingdom, near mint, their price list as of .
Kirk, Alluring Upstart 
Sisay, Weatherlight Captain
Legendary Creature — Human Soldier · 2/2 · Mythic · Stardates · #4
Sisay gets +1/+1 for each color among other legendary permanents you control.
{W}{U}{B}{R}{G}: Search your library for a legendary permanent card with mana value less than Sisay's power, put that card onto the battlefield, then shuffle.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
7 printings · $2.99 to $109.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 1 Timeshifts | 6 | Rare | — | $5.99 |
| Modern Horizons | 29 | Rare | $2.99 | $11.99Out of stock |
| The List | MH1-29 | Rare | $2.99 | — |
| Stardates (Kirk, Alluring Upstart) | 4 | Mythic | — | — |
| Secret Lair Drop (Buttercup, Provincial Princess) | 1444 | Rare | $64.99 | $109.99 |
| Secret Lair Drop (She-Ra, Princess of Power) | 2778 | Rare | $8.99 | $13.99 |
| Secret Lair Drop | 9999 | Rare | $8.49 | $10.99 |
2 rulings from Wizards of the Coast
- 14 June 2019If a card in a library has {X} in its mana cost, X is considered to be 0.
- 14 June 2019If Sisay leaves the battlefield after you've activated its last ability but before that ability resolves, use its last known existence on the battlefield to determine what cards you can find.