+1. Well said. I have listened to a variety of interconnects, power cords, and some headphone cables, and I've yet to hear one lick of a difference in them. I can, however, hear subtle differences between vacuum tubes of the same make, model, and manufacturer based on sample variation alone. Buying cables for anything other than style or looks is a fruitless exercise.
If you're on a budget ( or even if you aren't!) the first thing I'd do is forget about the cable upgrade. It won't do anything for you (sound-wise). If you're trying to upgrade looks or style, that's another story. It's amazing the way this nonsense has been ingrained into the buying public.