Go to
www.randl.com and buy from them, but i would also suggest you change from 9913. Don't get me wrong its darn good coax, but make sure everything is WELL sealed as the air core can take on moisture. I have cut off the PL-259 at the bottom of a run and had the water run out on some installs. I ran it for years here, never had a problem, but it was SEAL SEAL SEAL to make sure.
Also, just a suggestion on the coax...
Jetstream
JT2013 Similar in loss to 9913 but with a solid poly dielectric, no air core. Solid center.
JT2015 Similar in loss to 9913 but with a solid poly dielectric, no air core. Stranded center, more flexible.
If you need a truly flexible version, to go around a rotor, go with JT2015F, its the same as the 2015 but with a Foam dielectric instead of the poly, much more flexible, even at the -20 we have had lately for air temp. I have over 500ft of this in use here, nothing but good results and compared to my 9913 in a 100ft length identical loss wise but cheaper!