I have RG-142B/U coaxial cable for sale which is unused stock. This cable has a silver plated double shield and an insulation made from PTFE. Therefore you can solder this cable without melting the insulation. This type of cable is often used for phasing lines. I ask 3,-€ per meter which is some 23,-DKK, plus shipping from my QTH in Kiel (DL). I will sell short pieces or long runs, just tell me what you need.
73 de Andy DH5AK