I have some nice WR90/WG16 waveguide relays for sale :

3 port Waveguide relay WR90/WG16 24V The relay has a very small footprint.

Perfect relay if you don’t want any loss in your tx/rx switching relay, also perfect to use together with a DB6NT waveguide preamp.
Insertion loss < 0.1 dB Isolation > 55 dB
Price Euro 125.

18 GHz SMA relays

Also have some nice 18 GHz 28V SMA relays. Insertion loss < 0.3 dB 3 GHz.

Datasheet

Price 30 Euro