Cheapest priced copy (Lorwyn): $2.29 at Card Kingdom, near mint, their price list as of .
Merrow Harbinger 
Creature — Merfolk Wizard · 2/3 · Uncommon · Lorwyn · #73
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When this creature enters, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper