Are you planning on using it mounted on the camera? If so, then here are a couple of thoughts:
First, unless you’re always going to be two feet away from your subject, on-camera shotgun mics are really only good for picking up ambient sound. So, if you’re planning on getting good dialog or speech of any kind, you’ll need to go wireless or hire a sound mixer/boom operator :o)
Second, for the EX-1, I would recommend the Sony ECM-673. It’s the shortest, one of the lightest, and one of the least expensive ones out there. It’s also been sold out at B&H for months, though. The other mic you might look at is the Rode NTG-1. It’s about an inch longer but around the same price as the sony ($269.95). Remember, these mics are only really made to capture ambient sound and not clear dialog or speech. And, anything longer might stick into the frame on wide shots.