How much money on speaker cable?

To put things in perspetive - $600 is probably way more than the cost of the components (drivers and crossover) in your speakers. There is actually a greater length of wire in your speaker voice coils than your speaker cables anyway.
For example, $600 will buy you a world class pair of studio headphones (including the wires to the headphones).

Also check out JPS Labs, and, Analysis Plus cables. Both outstanding cables for the money although I prefer the JPS by a wide margin.

Spend as much as you possibly can on components.

Address cable requirements last.

Good components and average cables will outperform the reverse in most systems.

Your going to get alot of responses like....cables don't matter...or here is s cheap alternative...do not spend too much...When In fact it does matter. I'd look at some used or closeout Audioquest DBS cables and if you could get silver interconnect...and maybe speaker cable. Your safest bet for Neutral, detailed but coherent cables. First time I listened to AQ cheetah with Kilimanjaro I could not believe how organic and real the music sounded.

thanks everyone for your opinions. I do plan on addressing cables last but if i had the extra cash afterwards, would more expensive cable would enhance my experience?