Least Expensive Power Conditioner/Surge Protector That Won't Worsen Sound

+1 on Chang Lightspeed

Brick wall out of PA for $300, matched several-line conditioners in the $1500 

range andSterphile used to have it in class-B  which is respectable ,I bought 2 and find them pretty effective ,I upgraded mine by upgrading  several internal capacitors 

and installed a Furutech power cord to make it better still , most everything can be bettered if you look inside it ,whst most Audiophiles don’t realize is Thst on average 25% of the-cost goes into the build ,the rest R&D  overhead,and dealer mark up.

If they are doing it right, parts are marked up 5 times in manufacturing. The other costs you mentioned should be marked up 3 times, including labor. Then, that price is doubled twice before the point of purchase. The margins in audio are what makes it all go round. 

I avoid using the AQ Niagra high current outputs and now plug my amps directly into the wall socket- Proves to be sonically inferior through the AQ Niagra

To me this unit was a total waste of money .

Furman Elite 15PFIs - good units, and you can find these used at good prices at Audiogon, US Audiomart, and HiFi Shark.