Buying or selling used hi-fi--before the Internet--was a huge hassle. Expensive classified ads in newspapers and magazines were the only option for individual sellers and buyers; that, or trade your gear in to a hi-fi dealer.
Nowadays you can buy or sell hi-fi and pretty much everything else on eBay, but I've never used it. I've always sold my old gear on AudiogoN, which specializes in high-end audio components, such as preamplifiers, power amps, speakers, CD players, turntables, cables, etc.
If you're looking for great sounding bargains, you'll find plenty on AudiogoN. I saw a vacuum-tube Dynaco FM-3 radio offered for $139; a mint-condition Marantz 2220 stereo receiver for $245; an NAD 7100 receiver for $175; and a Dual 1019 turntable for $250. AudiogoN averages around 11,000 listings at any given time.
High-end gear that originally sold for big bucks is rarely cheap, because good, quality gear, even when it's decades old, retains its value. But even so, AudiogoN is a way to get the good stuff that would otherwise be out of range. I saw a Conrad-Johnson 16 LS vacuum-tube preamplifier that sold new for $8,000 listed for $3,500.
AudiogoN was founded in 1998 and now claims 295,000 registered members. Rates for sellers are just $6 for a classified ad (which runs 30 days); or $6 for an auction, that runs between 3 and 14 days. There's also a one percent surcharge on the sale price. Buyers pay nothing for the service. Best of all, almost everyone reading the listings is an audiophile, which certainly isn't the case for eBay. Here's a link to a mock ad, so you can get an idea of what they look like.
Manufacturers and retailers also advertise and sell gear on AudiogoN, and there's a wide range of active forums for audiophiles of every type.
I've sold every listing I've ever placed on AudiogoN. The transactions all went smoothly, and I've been impressed just how friendly every AudiogoN user has been. The site's staff scrutinizes all the new postings, on the lookout for anything that doesn't look kosher. If there's a problem the Audiogon staff gets involved and works to solve issues between sellers and buyers.
One of the great things about buying used gear, other than just saving a lot of money, is that you can experiment and live with a range of different components. Smart buyers can resell the amp or speaker they bought six months ago for about the same price as they paid for it.
Looking to buy or sell a TV or Blu-ray player? Check out AudiogoN's sister site, VideogoN.
If you've used either site, or eBay to sell or buy gear, tell us about your experiences in the Comments section.