You could order a 20 amp IEC female plug online and then buy a suitable length of 12/3 power cable from your local Home Depot and put a high quality plug on the end.

Or you could go here:

www.quail.com

and order a custom cable. I think the connector you want on the equipment end is a IEC-60320-C19. But perhaps someone else on the list can confirm that.

Cheers,