Our team is looking for plastic gears available online. The exact dimensions are: 12 pitch with 14.5° pressure angle. Our main problem is finding a source with the selection we need. Is there a good source that would carry this size gear?
If you decide to use plastic gears make sure you don’t put any sudden loads on them. We tried to use it in 07 and ended up spraying plastic teeth all over our shop when the arm came down fast.
Check out WM Berg. They have a ton of choices, but not sure if they have what you are looking for.
www.sdp-si.com all you need for the hard to find transmission components.
and their website has reciently gotten better.
Beware of plastic gears, although they are lighter. Make sure they can handle the applied loads.
try rushgears.com 
I took a glance at SDP when I first saw this thread, and from what I saw, they don’t carry plastic gears under 16 DP.
I stand corrected. They have loads of plastic gears but 16DP is the minimum.
Mcmaster has a lot. They are expensive as heck. Consider yourself warned.
You might try Boston gear.
-Vivek