Well, percentages are nice when estimating expenditures, but they are merely guides, not ironclad principles.
With my new ATI amps, the whole two-channel system comes almost exactly to $50k. It breaks down like this:
20 Amp circuit 0.3%
balanced cables, etc. 0.1%
In our more costly HT, room treatments accounted for a full 5% of the cost while speakers were closer to 50%.
A lot is room dependent where treatments are concerned. A few bucks might work in one room and a few thousand in another.
Getting back more specifically to amps, I really need amplifiers that can do certain things for me, and the ATIs have all that, plus more. I want to go full balanced instead of single ended, and ATI handles that, plus the "true balance" differential design architecture of the amp really fits the bill for me. I want lots or headroom, and with three 200W channels per amp being fed off two gigantic toroidal transformers, there's no bottom to this well--or at least I can't find it.
About that 200W/channel--it's not really true.
Are they liars? Well, no, my actual measurements find them to be running about 210-220+W/channel, all channels driven from full range 20Hz to 20kHz noise. So it's not your typical, lame 200W/channel with one channel driven only at 1kHz.
A nice surprise is the soft start circuitry. I have a single 20 Amp circuit dedicated to this system, and with the amps connected via DC triggers to the pre, a push of the on button brings the whole system up in an orderly fashion, without pops, thumps, thrown breakers, or house wide brown outs. I can take the Niles IPC6 sequencer right out of the system.
All in all, I got everything I needed in an excellent pair of amps at a great price, made locally in CA, USA. Plus, I didn't pay extra for what I didn't need: fancy billet Aluminum front, big prestige brand name, expensive marketing campaign, and huge overhead. Instead, when looking at them up close, I can see the quality construction, the attention to detail, the careful engineering, and the thoughtful, useful feature set.
These are well worth the $$$$ as the OP first asked the question.