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.)
"Hup, two, three, four, Dunno how to count no more." —Mogg march
NM-Mint - $24.60
NM-Mint Non English - $24.60
Lightly Played - $23.40
Lightly Played Non English - $23.40
Moderately Played - $22.20
Moderately Played Non English - $22.20
Heavily Played - $19.70
Heavily Played Non English - $19.70
Damaged - $16.00
Damaged Non English - $16.00