what are your top "audio bargins" in your system history?

I would have to say a Marantz 2265B reciever that someone gave me back in the early 80's  That was the beginning of my audiophile journey 

Recently l bought a used Spectron musical MK lll class D amp designed by John Ulrich and the old beast almost weighs 60lbs 

Years ago I purchased a VAC CLA1 MKII Pre, Counterpoint NPS-400, Clearfield Continental speakers with Synergistic Research cables for $300 and then spent $300 on tubes and a repair. I still have and use the VAC in my second system.

Bought a set of B&K Sonata monoblocks along with matching B&K Pro 10MC preamp for $450 about 10 years ago. Best bank for the buck I have ever come across. 

Wish I still had them.

New Large Advents $150

Klipsch Heresy "Decorators" $300

Infinity RS-II towers $400

ATI 1502 $150

I still have the Advents and the ATI amp.

New Large Advent Utilities, $148(?) at Tech Hifi in 1978 as a HS graduation present. Refoamed by Miller sound. Still in my secondary system

Ohm Walsh 2000s for $2800/pr in 2009. End game speakers for me.

A pair of Vandersteen 2Wq subwoofers bought used for around $800 each. Never will they leave my system.

Arion Audio S500 stereo power amp. Got a special price on this one, but even at it’s list price at the time, $2500, it does everything I want an amp to do, nothing I don’t, and I can carry it under one arm if I need to.

Highly modified Beresford DAC by K Works. Only goes up to 96/24 and lacks USB input, but outperforms modern DACs costing much more. I paid $500 used including power supply.

Custom Sound Anchor stands for the Ohm speakers. Solid, effective and affordable.