Wood Bull Antiques is on NY State Hwy 28 just north of the Village of Milford.  This is about half-way between Oneonta/I-88 and Cooperstown.  Going North from I-88, stay on NYS Hwy 28 7-8 miles until Milford - after the traffic light, look on your right for the festival in front of a big barn!
From the north, go through Cooperstown to NYS Hwy 28 south, drive about 8-9 miles and look for the festival signs just before you reach Milford!