Cheapest priced copy (Modern Horizons 3 Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Riveteers Charm 
Instant · Uncommon · Streets of New Capenna · #331
Choose one —
• Target opponent sacrifices a creature or planeswalker they control with the greatest mana value among creatures and planeswalkers they control.
• Exile the top three cards of your library. Until your next end step, you may play those cards.
• Exile target player's graveyard.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.35 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 3 Commander | 271 | Uncommon | $0.35 | $0.49 |
| Streets of New Capenna | 217 | Uncommon | $0.35 | $0.49 |
| Streets of New Capenna | 331 | Uncommon | $0.35 | $0.49 |
| Streets of New Capenna | 396 | Uncommon | — | $0.99 |
2 rulings from Wizards of the Coast
- 29 April 2022For Riveteers Charm's first mode, if the target opponent controls more than one creature or planeswalker with the highest mana value among creatures and planeswalkers they control, that player chooses which one to sacrifice as Riveteers Charm resolves.
- 29 April 2022For the second mode, you must pay all costs and follow all normal timing rules for cards played this way. For example, you may play lands this way only during your main phase while no spells or abilities are on the stack and only if you haven't played a land yet this turn.