Best Power Cord

I am in the process of replacing my MIT Z cords on both my Bryston 9B THX amp and my Wadia 850. The system that the 850 is in has synergistic cables throughout and a Master Coupler for my Pass X-150. The Bryston is in my HT system and I use a combination of Nordost I/Cs and HT Pro 9 speaker cables.

Any thoughts for power cords for either or both of these components would be appreciated. I am thinking of perhaps a Black Mamba for the 850, but have read mixed reviews of that P/C. I also am thinking about a BMI Whale for the Bryston, but have not heard the whale yet. Any other cables I should be considering. I would like to stay in the sub $600 (used) price range.