I’m not sure throwing out a figure representing the retail value (or actual amount paid) tells you much. What about the person who has purchased equipment in considered fashion, perhaps ten years ago or more? Is that a lesser system, qualitatively, than one that someone spent double the amount on? Would you make that determination based on the retail price of the equipment? What if some of the gear was truly vintage? Retail pricing was very low compared to today, for that same thing.
If you are about getting a sense of the demographic, how much people are willing to spend, I’d say it is all over the map. I have a system running that emulates what I was running in 1975. Some of the components in it were purchased even earlier than that date. My sunk cost is almost nil, and the cost of refurbishment was trivial considering the quality of the gear.
My main system was pricey but well thought out. It is not the same as other systems that cost the same because the particular choice of components, set up, etc. all vary by user/room, etc.
What is it that you are trying to find out, OP?
If it is the "philosophy" behind building a system, how does the grossed up retail price tell you anything about that?