Cheapest priced copy (March of the Machine): $0.35 at Card Kingdom, near mint, their price list as of .
Assimilate Essence 
Instant · Common · March of the Machine · #47
Counter target creature or battle spell unless its controller pays {4}. If they do, you incubate 2. (Create an Incubator token with two +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| March of the Machine | 47 | Common | $0.35 | $0.49 |