There are three established shops on the NJ shore - from N to S.
Bayhead Windsurfing - Bay Head Trading Co., 520 Main Av, Bay Head, NJ
http://www.bayheadtrading.com/
Island Surf & Sail - Long Beach Island, NJ
http://www.Islandsurf-sail.com/
Extreme Windsurfing - Jim Karabasz - Atlantic City, NJ
http://www.extremewindsurfing.com/
Suggest you contact each for information about used equipment, swap meet, demo days etc. or visit some of the more popular sailing sites and see what equipment is most likely to meet your sailing level and areas where you plan to sail.
Perhaps visit Sandy Hook on N.W. day or Sea Side on SW.