Try your local 'electronics' store (not stereo store) and get some heavy guage Belden cords. They are cheap and good.
Where to find quality "stock" power cords
I just sold a pair of monoblock amplifiers but could not locate the stock cords that came with them. I promised the buyer I would supply these. For a high-power amp from a big name high-end company, this is normally a 14 awg shielded PC. Should be easy enough to find, but I've not had luck. Suggestions?