I own not one, but two Monster power conditioners. HTS 5100 Mk II. I paid far below retail (wholesale cost, in fact) and Monster Power products are hardly snake oil compared to their interconnects. I do regret giving such an evil company any of my money. I also own more Monster cables that I care to admit. They're mostly S-Video cables, but I also have some of their coax digital cables and a few of their lower end analog RCAs (which don't have their idiot "bandwidth balanced" geometry. With the exception of maybe one, I paid a fraction of retail for all of these. I still should not have bought them. Oh, I also have one Monster power strip, for which I paid $0. I would like to purge all of the Monster from my house, but realistically, I'm only going to get rid of the power conditioners. If I can sell off a few more worldly possessions, I'm gonna spring for a couple of those APC refurbs.
Also, I own a pair of Sony MDR-V700DJs, which are the worst headphones in existence. I bought them in 1999 or 2000, when they were a then-new product, and every DJ had to have a pair. I have atoned for this sin fully by owning MDR-7506s for nearly as long, and upgrading them to Beyer pads. I also have some HD-280s. I was once tempted by a pair of Ultrasone DJ-Pro1s, but I resisted, and I'm glad I did.
In 2008, my only major audio sin as been severe disorganization. I bought an upsampling digital source that's single-ended only right before I finally committed to going balanced.