I bought my wire from monoprice.com
GREAT cables/wiring for GREAT prices.

Some will say that you need to run 12ga wire, but 14ga is plenty for what your space is.

Also, many people are just as happy buying wire from their local home improvement store. Simple "lamp wire" is fine, but you should look for oxygen free, in my opinion, to reduce discoloring of the wires.

I went with in-wall rated, but you don't need to.
MonoPrice Speaker Wires

Of course, Axiom sells speaker wire! They are pretty spiffy too...
Axiom Speaker Wire

Farewell - June 4, 2020