Cheapest priced copy (Mirrodin): $0.35 at Card Kingdom, near mint, their price list as of .
Myr Prototype 
Artifact Creature — Myr · 2/2 · Uncommon · Mirrodin · #214
At the beginning of your upkeep, put a +1/+1 counter on this creature.
This creature can't attack or block unless you pay {1} for each +1/+1 counter on it.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mirrodin | 214 | Uncommon | $0.35 | $1.99 |