I am looking for dry ginger preferably in Brooklyn. I have tried the food coop. I'm not sure if it's a health food thing, or an Asian ingredient.
Try Penzey's at Grand Central Terminal.
I get mine at The Spice House (online or Chicago).
While ginger is beneficial to health, the dried form is common in baked sweets (i.e. ginger snaps).
You could also try a Chinese supermarket since one of the best varieties of dried ginger is the China #1.
You can try any of the Asian food markets in Sunset Park. It's usually candied so you might find it in that aisle or near the tea. It's great for nausea, particularly from motion sickness.