I never considered spending more than $20 on a power strip / surge protector until I bought an audiophile stereo system. The shop that sold me my turntable recommended a $500 power strip. Another shop recommended replacing the stock power cable that came with my amp with a $150 cable. Both recommendations were for sound quality, not surge protection.
I'm skeptical that these items would bring a sound quality improvement commensurate with their cost. If you have an extra $500 and want better sound quality, I'm pretty sure it would be more wisely invested in speakers or components.
While I wasn't willing to risk $500 for a power strip of dubious benefit, I was very willing to spend $150 on this Furman power conditioner/surge protector, and I'm glad I did. I can't say whether it makes my stereo sound better; if it does, the difference is subtle at best. But the unit is very well built, professional-grade as opposed to the cheap mass market power strips available at Walmart or your local hardware store. And it gives me peace of mind that my expensive stereo is protected from power surges.
I've purchased a few items for my stereo that might or might not deliver improved sound quality such as this power conditioner, an isolation platform for my turntable, a record puck, and an upgraded power supply for the turntable. It's possible I've wasted my money chasing tiny sound improvements. But my system sounds truly great, and my sense is that the combination of all of these items makes a difference even if some of them on their own make little to no difference.