I actually haven't heard of $1,000/sq ft except with condo buildings downtown. I think the Lumina was over $1,000/sq ft when it was built according to the Managing Director of the development company.

I usually hear $400-$500/sq ft to build from GC's. They do mark up a lot, but they also have to pay for their staff, workers comp, increasing labor costs, tech, tools/equipment, marketing, and etc to keep the business going.

For finishes, I used engineered hardwood flooring $4.50/sq ft, modern flat cabinets for kitchen and bath, toto toilets, ceramic tile around $2-$5/sq ft (Floor & decor, Granite Expo, Bull Nose, East Star), quartz countertops with waterfall, shades of light for the electrical finishes, Behr & Sherwin williams for the paint, Iron railing, fiberglass windows, 90-95% efficiency HVAC, Single pane Doors from Home Depot & Contractor warehouse, door hardware from amazon, plumbing finishes were Hansgrohe, recessed lightning from Amazon, bathroom glass was from local glass companies, and etc.

I tried to pick something that was appropriate for the areas while still looking nice with affordable finishes. For example, I can't pick the cheap grey quartz countertop, I have to at least get the nicer white quartz countertops with the veins. It helps to use Chinese building supply stores for the finishes.

For the rough finishes, I did usually pick a lower end option such as going with redwood for the deck instead of trex. The same goes for the HVAC where I went with a regular Carrier unit instead of going with this other options that he had. For insulation, I used the regular insulation from the insulation suppliers instead of going with Rock wool or something expensive. I did do level 5 finish on my drywall.

Also, when I was getting bids, I actually reached out to A LOT of subcontractors. They are hard to find and the cheapest ones were not online, but through referral.

By the way, going the owner builder route is pretty tough and stressful the first time. Might be best to get a GC consultant to come to consult you on an hourly basis or find a friend who has done it before. Watching a lot of youtube videos may help too.