the retail cost of everything in my present system is ~$45k. what i paid for everything in my present system is ~$12.5k. only my vmps subwoofers were purchased new, & i got a decent discount on them - but still nothing like purchasing used. the only thing that was purchased new that's no longer in my system is my marchand crossover, recently replaced by a used deqx. i imagine i might lose a couple hundred dollars on it if i sell, but everything else i have bought & sold i have at least come out even, due to smart shopping whilst buying used.
i have enough gear not in my main system to set up several more - but the cost-vs-retail of this gear is similar. whenever i sell anything, i always at least break even. recent example - mitsubishi da-f20 tuners in good shape usually sell for $250-$300. i used to own one before, & it's so good, i always regretted selling it, w/o having it modded first. it was in the same league stock as my stock sansui tu9900 & accuphase t101 - the tiniest bit better than these two, actually. well, i stumbled across a da-f20 plus matching mitsu amp on ebay, with a buy it now price, or best offer. it had just been listed. so, i shot the seller a ridiculous (imo) offer, & to my surprise, the seller accepted it. so, i got both the amp and the tuner for $290 shipped. the amp is actually wery nice; it's been in my system for a coupla weeks. but, i was happy to let it go for $240, on ebay; it yust sold this past sunday.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=140173436392 sometimes, i buy something knowing up front that i will be re-selling it for a profit. several months ago, there was a foster blair refurb's scott tuna & mpx f/s on agon for $250 shipped. i used to own this exact same combo, but not worked on by foster - one of the premier scott techs in the country. as i knew the mpx's alone usually sell for that, or more, even if never serviced, i immediately emailed the seller accepting his asking price - hoping i'd been the first offer. well, i was the lucky buyer, i enjoyed these fine musical instruments for a while, & then i sold 'em on ebay for $410.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=140173453593(ironically enuff, foster blair himself bought 'em!

he's gonna go thru 'em again, w/more modding this time, & sell 'em thru mapleshade, which adwertises modded/refurb'd scott gear on their website.)
this is how i usually buy gear - i decide what i want, & then wait for something to show up used, where i know i will be able to resell w/o taking a loss. every once in a while, i get lucky, & actually make a few dollars.
so, upgrading my system has been a small money-maker for me, actually. the only time i get burned is when i have bought something i do not wanna sell, so it is stored, or in a second system, etc...

doug s.