Parasound Zamp3 is my number 1 answer, just love that little sucker.
Schiit Saga Pre, simply operation and transparent as can be.
What are/were the best sounding cheap components you have ever had?
It is easy to like the best of the best, so to say. However it is always satifying and memorable when an inexpensive product turns out to be very good to great.
Some that come to mind from personal experience"
Large Advents (original)
Early Nakamichi SR receivers
Original Monster interconnects and speaker wire
Pioneer Pl-12 turntable
Shure M-95
Early Stax and Audio Technica headphones
MoFi "special" pressings
Magnum Dynalab Etude. Yes some were better, but a real value
The Absolute Sound mag in the beginning
Early Conrad-Johnson and Audio Research tube electronics
Early Classe integrated amps.
The original Sony Trinitrons
And there are others....but part of this hobby is enjoying the journey.
Have you had cost effective items that were successful for your enjoyment?