At below 5C my RF400UF with SMA is a nightmare to connect. Even RG400 + SMA is bad. It’s why I do almost no 13cms in the Winter.
You just don’t see many of them surplus and so don’t build up junk stock. I’ve been collecting quality junk for 40 years. I have stopped now as I have enough! I bought a bag of BNC bits at a junk sale, it contained 25 chassis mount socket, 30 panel mount sockets and uncounted amounts of plug bodies, teflon pieces, cable clamps etc. Along with 40 years of skip diving I have enough solder BNC parts. I’ve only bought BNC crimp recently and I think I bought some BNC <> RG213 30 years back.
In the TNC world I have a TNC to BNC which goes on the Marconi TF2015 sig gen frequency meter output to the meter. Sadly when you take the blanking plug from the TNC socket on the TF2015, the leakage swamps the attenuated output… it doesn’t get used much. I have a few old ETACS car mobile phone units from the late 80s that run about 10W on 920MHz. These may have been used for clandestine talkback operation 30+ years ago 
We had a PSU for a big valved PA that used a TNCs for the HT feed. Wouldn’t want to confuse 2.5kV with small signal path so TNC was HV safe and couldn’t be confused with BNC or N signal connections.
So that’s a total of 4 devices in 32year ham career that used TNC. Shame, it’s a good connector.