It would really depend on the Coop. They all have different requirements. If the coop allows you, you can do as little as 10% down.
On a Condo, it its an FHA approved condo its 3.5% down. If it is Fannie/Freddie approved, you can do a 5% down payment.
Call me.. I have closed in many of the Condos & Coops in the area. I can walk you through the inventory..