Need source for wave guides.
http://www.maurymw.com/Precision/Waveguide_Components.php
If looking for used try Western Test Systems. We have purchased from them and had no problems with any parts.
http://www.westerntestsystems.com/
There's also Pasternack
http://www.pasternack.com/
I'd try Millitech - they bought out the old Hughes microwave line of products in the 90's.
http://www.millitech.com/index.htm