Biggest "bang for the buck" audio gear you have owned(in your history)?

This is very subjective, and your opinion on your own systems/items is all that really counts.

From the beginning to now, these would fit that category for me: (in no order)

Original Large Advents
Dahlquist DQ-10
Conrad Johnson ART pre.
Original Monster interconnects and speaker wires.
Nakamichi SR-3a
AR Turntable
Audio Research LS-12
Magnepan 1.6
Magnepan 20
Wireworld Gold Eclipse III
Audio Technica Electret Condenser headphones 
Magnum Dynalab Etude and 108 tuners
Magnum Dynalab Receiver (original)
And in those "early days" special pressings and imported Jazz albums. 

There may be others I am forgetting, but these were very good items along my journey. 

Noe there's a brand you don't see very often. How did you end up with it? Are you near their shop? I check out their website every once in a while. Their range of product is impressive

I was looking for a new tube preamp and didn't want to spend a fortune, they had a lot of positive feedback and a used qa112 for $750 so I bought it. I also found a used separate power supply for it at the music room for $450, it's called a super rectifier and uses large 4 pin half wave rectifier tubes. 
Parasound Halo Integrated Amp
Actually anything in the Parasound Halo family.
Outstanding gear-Incredible support.
I was pleased to see the Large Advents mentioned.

 Large Advents
LBL L-100
Dahlquist dq-20s
Hafler Amp and pre-amp I built 
Roger Modjeski pre-amp

They all brought good music at great value but the only one I widh I had not sold was the Roger Modjeski pre-amp.