You can get those from Eheim directly.
www.McMaster.com has a lot of other valves that perform the same function as well. If you are making the air trap that is in the pics, you don't need the valves. Those are good for priming an inline, non-reservoir system, but if you have an air trap like that, the valves don't serve too much of a purpose as long as you can fill from the reservoir.
-Kevin