So running "cost" numbers for the aformentioned "massive" orbital arcology, all prices in MCr.
Base Hull: 3,366
"Day/night: panels: 1,683
Life Support: 7,540 (note 1)
Solar Panels: 3,000 (note 2)
Solar Cells: 4,500 (note 2)
Total Arcology Cost: a hair under 20,100 MCr
For a population density similar to the Netherlands, this is an investment per person of just under 500,000 Cr.
For a family of 2.5 this would require a "Family Income" of 250,000 Cr/year (assuming a 25 year mortgage at ~5-6% interest) Given that development of this type is likely partially subsidized and / or allowed to be amortized across a longer period.
Using a 40 year term, the same as starships, the "Family Stead" would be a monthly payment of Cr 2,604, or an annual payment of 31,250 Cr. This assumes that this structure is the personal property of those folks who live there *with no corporate or government ownership whatsoever*
My guess at property ownership in "western" countries would be that about 10% of the land is owned by "middle class" citizens, with the rest owned by governments, corporations or the "super-wealthy". If the "Family Stead" is only paying for the property that it directly sits on (200 square meters/10% of the average area per citizen, and this is probably generous) then the annual payment is reduced to a little over 3 Kcr, probably well within the realm of the TL-11 "Average Joe", even with a "stay at home" parent.
If solar costs are brought in line with nuclear plants, then the cost of this arcology is reduced by almost half, with the vast majority of the "cost" being the life support cost: reducing this by a further order of magnitude puts the "base" hull at around 6 Billion Cr. At this price, if the "Average Joe" family can afford to put 10 kCr a year into "housing" expenses, they can but arcologies outright.
For "Canonistas" the full cost using 100% power (the "cheap" fusion way, no solar arrays) and cost for type-4 life support would be in the 850 billion range, a factor of 40-ish increase, almost entirely because
1) life support is volume based, not biomass based.
2) We don't have life support numbers for anything other than starships.
In this scenario "Average Joe" rents, or lives in a shoebox.
Even with this "worst case" scenario this construct is still several orders of magnitude less expensive than construction using CT / HG. Even if it models only the structure and life support. This is "virgin" land and would need industry, commercial development agriculture, transportation infrastructure and housing to be fully fitted out.
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Note 1: Life support cost reduced by a factor of 100. Life support "power" provided by "windows" to provide power with an efficiency equal to solar panels at the same TL. This provides sufficient power to meet the (exhorbidant) life support power costs. Solar panels provide 0.15% of this "required" power, which should be sufficient to run pumps, recirculation motors etc. Failing this, dump the solar cells, spend as much on a fusion plant and assume that a "fixed" life support installation takes up more volume but is 1/10th the cost.
Note 2: Whay are solar panels so damned expensive in FF&S? a fusion or fission plant with the same output at tech/11 would cost 105 MCr. (about 1.5% the cost) For some reason components with much lower tolerances and a massive surface area penalty which should be significantly easier to manufacture cost more than 70 times as much for the same output! This is an area that I would flag to be fixed for FF&S-3...
Scott Martin