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

This one is easy...I bought one of the Carver "The Receiver" and I ended up counting the hours until that thing sold in the newspaper classifieds.  It literally sounded awful.   I don't think there was anything mechanically wrong with it, it just turned my Infinity speakers into echoing soup cans, and not due to an impedance or power-requirement mismatch. 

The shame is, I’m sure Carver makes lots of great gear (I assume?) but after that purchase I’ve never been able to go back to that brand.

The worst purchase I ever made was before I even had a system that could be considered high end. It was 1984 (or so) that I decided those newfangled CD players thingies had come down enough in price to warrant buying one.  I read every issue of the known bible (Stereo Review) I could find that talked about CD players, and finally decided on a $400 Onkyo player with the heavily marketed "Opto Coupling" between the digital and analog sections. Brought it home, hooked it up, and immediately went through a whole roll of Bounty sopping up the blood pouring from my ears.  I didn't know about things like break-in back then, but even that wouldn't have helped this player.  Took it back to the store and told them it was defective.  With no questions asked, they took it back and ordered a replacement.  When that arrived, I took it home only to experience the same unlistenable dreck.  The store had never really offered any money-back guarantees, but they were good enough to take back the 2nd player and give me store credit for the full purchase price. 

I didn't even look at another CD player for over 5 years....

A turntable that cost as much as a nice car but I rarely use.

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).