Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)
NM-Mint - $18.20
NM-Mint Non English - $18.20
Lightly Played - $17.30
Lightly Played Non English - $17.30
Moderately Played - $16.40
Moderately Played Non English - $16.40
Heavily Played - $14.60
Heavily Played Non English - $14.60
Damaged - $11.90
Damaged Non English - $11.90