If you are not building a new house, how much would it cost to install (retrofit) a whole-house surge protection?
Yeah, I think most people don't have Whole-House Surge Protection or even know about it.
When I built my new house, I had to emphasize several times to my builder and electrician that I absolutely require whole-house surge protection. Otherwise, they would not have done it.
Like you said, most of these AVPs and AVRs are so complex these days. Any significant component failure will usually require purchasing a new AVP or AVR.
The cost of new/old construction will be the same. The bigger issue is separation of meter/entry point and the electric panel. If the two are close you can get away in a single phase home with
a unit like this and the unit can be placed inside. That was the case at our lake place. The total cost with installation should be around $300 to $350.
On the other hand, if like in our new place the panel is a long way from the meter, then you need an outdoor rated unit at the meter. That is what I did here as the panel is in the utility room which is upstairs and on the other side of the house. Here our 'basement" is upstairs. There is nothing below ground. I have had enough of basements in this part of the world.
So you would need a unit like this. That would get you into the $700.00 range. Well worth it.
However this should be combined with a Smart fast acting UPS. These will shave and increase voltage to keep voltage tightly controlled and switch to battery if the line is out of spec.
I have a UPS in the bottom of the three AV room racks, and one in the family room system and our in wall system. They power everything except the power amps. They power the whole IT system, Ethernet/cable modem, router, patch bay and hubs. Since bringing up the IT infrastructure over three months ago now there have been zero glitches and zero need for reboots.
I had an alarming incident at the lake a while back. It was on a national holiday of course. I noted that the voltage shave light was on on all four of my UPS units. (I had four there, but five here). So I checked the voltage and it was up to 139 volts. So I went off grid as I had a generator there and do here. I phoned the power company, who at first thought I was a nut job. However I convinced them there was a problem. By the time the power company got here the voltage had climbed to around 180 volts. A regulator at nearby County road 39 had gone rogue. If it had not been for those UPS units I, and a lot of others would have had enormous damage and may be fires.
My third level of protection is a whole house 30 HP generator. The former one was a lovely vintage Wisconsin/Kohler RMY V4 unit. This one is new, and a Cummins V2.
The cost of doing this has really come down. So in severe electrical storms it is my practice to take the residence off the grid. However the main reason for that is that I have issues where I can not be left without power.
I do think whole house surge protection and UPS units are well worth it. I think together they can probably prevent a lot of equipment failures. It is not just surges you need protection from but transient and not so transient line variations. I would bet that my investment in protection has paid for itself a few times over.
Lastly if your voltage stabilizer/controller does not have batteries, it is not adequate.
You would be surprised how often they show either lowering or increasing voltage and at times switching to battery when there are no storms or anything untoward going on.