Cheapest priced copy (March of the Machine Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Saheeli, Sublime Artificer 
Legendary Planeswalker — Saheeli · Uncommon · War of the Spark · #234
Whenever you cast a noncreature spell, create a 1/1 colorless Servo artifact creature token.
−2: Target artifact you control becomes a copy of another target artifact or creature you control until end of turn, except it's an artifact in addition to its other types.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
9 printings · $0.35 to $15.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 935 | Uncommon | $0.39 | — |
| Aetherdrift Commander | 119 | Uncommon | $0.39 | — |
| March of the Machine Commander | 338 | Uncommon | $0.35 | — |
| War of the Spark Promos | 234s | Uncommon | — | $1.79Out of stock |
| War of the Spark Promos | 234s★ | Uncommon | — | $15.99 |
| Secret Lair Drop | 534 | Uncommon | — | $1.99Out of stock |
| Secret Lair Drop | 1143 | Rare | $9.49 | $11.99 |
| War of the Spark | 234 | Uncommon | $0.35 | $4.49Out of stock |
| War of the Spark | 234★ | Uncommon | $0.99 | $11.99Out of stock |
8 rulings from Wizards of the Coast
- 3 May 2019If an effect begins to apply to the target artifact before it becomes a copy of another permanent, that effect will continue to apply.
- 3 May 2019Saheeli's first ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
- 3 May 2019If the target artifact is an Equipment attached to a creature and it becomes a copy of a non-Equipment permanent, it becomes unattached. If it becomes a copy of an Equipment, it remains attached.
- 3 May 2019The target artifact is an artifact in addition to whatever types the second target has, and this exception is copiable. If something else copies the artifact later in the turn, that copy also will be an artifact.
- 3 May 2019Saheeli's loyalty ability causes the target artifact to copy the printed values of the target permanent, plus any copy effects that have been applied to it. It won't copy counters on that permanent or effects that have changed its power, toughness, types, color, or so on. Notably, it won't copy effects that made the target permanent become a creature.
- 3 May 2019If the target artifact copies a permanent that's copying something else, it will become whatever the target is copying.
- 3 May 2019If the target artifact isn't an Equipment and becomes a copy of an Equipment, it'll become unattached when it becomes a non-Equipment artifact again.
- 3 May 2019If the target artifact becomes a creature the same turn it enters the battlefield, you can't attack with it or use any of its {T} abilities unless it has haste.