What's the most overrated or overpriced piece of equipment you own, have owned or come by?

My biggest disappointment is having bought the simaudio 740p preamp brand new after reading so many rave reviews on this unit. Usd9k
Sold it for half the price in just 3 months.
Compared to my aged aragon 28k, it sound veiled, lacked dynamics, muted highs and muddy bass.

I swear i would never touch this brand ever. I really wonder what the heck those reviewers are hearing.

zavato:  Wow, you must have gotten a lemon of a Thorens.  I bought a TD-166MkII new in 1984 and it is still in regular use (slightly modded). 

I regretted buying the Dynaco 416 amp with the outboard C-100. I had heard it in someone else's system and I was enthralled with the immense power and the flashing LEDs. I got it home and immediately blew out 2 pairs of speakers. But it wasn't until I switched it out for a pair of Mark III monoblocks that I knew I had made a dreadful mistake. 

I also regretted buying the Magnepan 2Bs until I got them into the right room and learned how to position them. 

But generally I buy used and more than 5 years old, so I don't get much buyer's remorse. The only exception to that is cartridges and CD players, which are the only things I have bought new in the last 20 years. 

But I am considering a NAS drive...

Odyssey Audio. By far the worst company and the worst products I have owned. The most positive thing I can say is this; After owning three pieces that had hum and buzz coming from the transformers and not getting in touch with the owner (no returned messages)  I finally reached him and returned the gear. It came back with the same problems. Mr K. lectured me on my power problems, even though countless pieces of gear never revealed this problem. So after years, not months, he agreed to buy it back at a huge loss to me. That is the good part.

I know there are fans, but I cannot see it from my vantage point.

2psyop: Sorry you had such issues with Odyssey Audio. I purchased a Stratos HT3 from Klaus (actually a one-off with new circuit boards for the L/R channels and an old board for the center channel) with cap upgrade following a little negotiating at an audio show. I had a hum problem as well. I was able to get Klaus’ assistant on the phone, and he walked me through the process of removing a ground wire inside the amp that he suspected was the issue. It was indeed the issue, and since then, which is about 10 years now, the amp has been totally silent. I did have one capacitor fail early on. While Odyssey Audio gladly and quickly replace it under warranty, I was a little upset by the large shipping charges required to send the 64 lb. amp to Minnesota. But overall, my experience was far better than yours, I think. FWIW, I love the sound of the Stratos. As they say, YMMV.