Henry:
I appreciate all your hard work and effort. I know firsthand how much effort it takes to build entire Webpages as I have done it as well.
I very respectfully disagree with your assertion that: "Cost: an O-gauge starter set or layout is at least twice the cost of an HO gauge layout of the same (scale) size and quality." I've personally seen O scale sets that were virtually given away at shows and after-Christmas sales.
I have put together a massive basement fill layout that has appeared in two professional videos, has its own YouTube channel and has appeared in three professional publications--The Glacier Line.
If you are a good shopper and bargain hunter, you may attain high-quality O scale pieces for the same if not cheaper than HO stuff which does not hold its value like O scale stuff. My benchwork, backdrops, paint, wire cost no more than an identical layout in HO. I have picked up Korber and 2 MTH buildings that cost (Korber) $170 new and (MTH $60+ new each) for $75 total. I have a small fleet of Atlas O cabooses that tops I paid $44 for one, the others were much cheaper--in$30s--new these are $80 bucks each.
The price of new HO stuff has reached new heights and as soon as you buy it the value plummets! I have purchased highly detailed and new priced expensive O stuff for $20 some odd dollars a car. And my these cars are still worth what I paid because I got them so inexpensively.
While I would concur that generally speaking, piece for piece, brand new price that yes probably most O scale stuff probably would cost more, building an O layout might not cost more if you know what you are doing and are fortunate. Stating that it would cost double is an assumption.
OFF TOPIC: I don't like the assertion either that O scale takes more space. It all depends. I have an O scale layout currently. I had HO scale layouts for years. ANY track arrangement that you can put on an 8 by 4 board in HO, you can duplicate in O scale. I have 12 radius curves, 24 diameter, on my O layout in places which is sharper than any manufacturer made standard HO curve.
I believe that too many folks get discouraged from getting into O thinking that they will pay double which isn't necessarily true.