Where to purchase cables?

I think you are requiring the assistance of a dealer. 

Or if you are going to go it on your own, since you posted here in Audiogon you might as well browse the cables ads. 

I've been extremely happy with my Pinetree Audio cables/speaker cables Excellent quality for the money and a pleasure to look at 

I’ve done a fair amount of a/b testing with Zu and 12 gauge cable.  I personally feel cables are complete ripoff’s. But there are audible differences.  They let you try them for two months for free. 
 

 www.zuaudio.com

I have no local dealers who stock cables I am interested in so I always borrow from the. Cable Company to see what does or doesn’t work in my system. 

I used the cable company lending library to evaluate numerous cables. Prices are reasonable and you have a couple of weeks to evaluate; but then I’ve mostly bought used.