Surge protectors--how many $ make sense?

Given the quality of the rest of your system, I would recommend as high a level as possible. Shunyata good choice. Definitely audition. But a good power conditioner will improve the sound yof all your components other than the amp (directly into outlet). There are isolated reports of a power conditioner not making a difference... very uncommon. Also, consider it a component you may never upgrade as you upgrade the rest of your system. I bought my 75lb power conditioner over twenty five years ago. It remains a core component... and when I have made comparisons... it is still of great comparative value. I’d audition an Everest. You'd never have to think about it again. 

Defense in depth: Absolutely begin with a whole house surgeprotector. It is the cheapest insurance known for everything electric in your home, especially if you lie in thunderstorm prone areas. If you have sub-panels, but one in their as well. Next is your point-of-use devices. Whether you decide to go with a simple quality suege protector, more elaborate power conditioner, or all the way to a battery power generator is up to you and your circumstances.

I would also check out Ting - www.tingfire.com - an electrical arc fault detector. State Farm just sent me one for free. Apparently they can detect 80% of all electrical fires before ignition. I get a monthly email report showing voltage fluctuations, outages, brown outs, and voltage spikes, which is kinda fascinating in a nerdy quasi-paranoid way. But the reassuring note that no faults were found does deliver some peace of mind. They're $99 with a year of monitoring, and include a pretty cool app, if your insurance company won't freebie one.

OP:

Be careful as some are marketed as "offers surge protection" which is different from having a UL or ETL certification as a surge protection device. Actual surge protectors will be certified to UL 1449.  It's the difference between throwing an MOV into the box and actually undergoing high voltage testing.

I have had great luck with using computer type Battery Backup/Surge protectors. My approach has been to use relatively high power units that will support a load of 1000 VA or more and use those in sufficient numbers to handle the current draw of the equipment. The good news is companies like APC will warranty the equipment connected for replacement cost up to a fairly high value...as yet I have never had to collect on that warranty and hope I never do. It is a source of peace of mind to know that the warranty is in place.

My power surges 2x a wk and I have furman 20 i that have never failed me.there are some on ebay open box about 2k.a whole house would be good as well.sorry it took a fire to stimulate.