Components first (seems you’ve got that covered), room next.
Then…power conditioner for your source, power cord for the conditioner, power cord for the amp, speaker cables next. Interconnects, USB, ethernet.
Get the best you can even if it is gradually one cable at a time. I’m not inclined to set budget limit of percentage of the component cost as I don’t adhere to any of these guidelines in my system. Get used from reputable sellers.
Order of importance and budget percentages
I’m redesigning my system again…. About to sell all cables and some gear to make a large upgrade
from really knowledgeable people please in a 50k or 100k MSRP system for example….
How would you spend your cable budget proportional to speaker, interconnects, power and Ethernet?