Berserk Mechanic

Berserk X (When this creature attacks, you may pay its berserk cost to double its power. If you do, sacrifice it at end of turn.)
Surprisingly it costs about exactly {0} to throw a one-cost berserk on a 1/1 body. Looking at doublestrike as a guideline, and taking into account that it sacrifices at the end of the turn. If this is a creature's only ability, it should be fairly balanced for Berserk {1}.