I didn't go through the whole list but
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shireeninc.com/I get most of my outdoor cat5 from them and have never had a problem with the cable quality. Shipping is pretty quick, normally same day. The in box spool sucks if you care to put it on a dolly though
. I would leave it in the box. But other than that...pretty good to deal with.
For networking there is of course your big distributors like DandH, Techdata, Ingram Micro, and a bunch of others.