There are a lot of windshields that will fit the Zero. Just get one that attaches to round handlebars, like the National Cycle Deflector Screen DX or the Slipstreamer SpitFire, which is the re-branded windshield that Zero sold for the 2012 S. The only hassle with these generic fits-all bar-mounted windshield is that they are a bit of a hassle to mount to a short, sharply-angled, tapered handlebar like is used on the 2014 Zero. You can make it work, but the taper confuses the bar mounts somewhat and they end up twisted a bit. Attached is a photo of the Zero Slipstreamer windshield attached to a 2012 S.
The nice things about the bar-mounted windshields is that they are relatively cheap, fit just about any motorcycle with round bars, are a good size to block the wind from your chest while leaving your helmet in the air, most (like the ones referenced above) can be removed and reinstalled in a minute once the bar clamps are installed and can be removed and installed on the next bike that you purchased. I have a couple of DX windshields that I have been using for over 10 years on various bikes and they just get removed from the old bike when I sell it and installed on the latest new bike. Very thrifty and efficient.