I once bought a "Heathkit" AP-2510 premaplifier on eBay for $22 (and free shipping). It's actually a Harman Kardon preamp (even the circuit boards bear the HK moniker - I know this because the "Tape 1" switch was flaky, and I had to remedy that with contact cleaner - works like a champ now) that in its day sold for around $300 or so; I use it as the preamp for the system in my guest bedroom.

Next, probably the M-Audio CX-5's. I have been able to find these for $129 each on line, and while they are not the all out best speakers available (but seriously...which ones are?...it's all so subjective), and since the topic thread was 'bargains', these certainly apply. Great deal for the money (they have been discontinued for a 'newer' model, but some can still be had as of this writing).

After that, I would say the Turtle Beach Audio streaming devices (Audiotron). I bought two new in '05 and '06 (while they were in production) for around $200 each (which at the time didn't seem all that expensive as I have a pretty big digital music library), but since then, I have been able to find several on eBay, one of which was $14 (plus $15 for shipping). Seriously...$14 for a component that was perfectly operable. I use the 'spare' Audiotrons in other rooms of the house (one of the Audiotrons interfaces to my 990 in my main system).

I have other bargains of course...but in my case, audio equipment is to me what heroin is to Scott Weiland...and as such, it seems there have been many 'sweet highs' (borne of bargains), and yet...I'm always on the lookout for yet another bargain, away from which...I cannot walk.