If this was possible, the competition would kill you.
Regardless of your numbers being wrong, it is the premise behind them.
Material cost = $540 + 10% markup = $600
Labor cost = $600 including overhead (50% of price).
I’m not in the industry, but I would think many very competent wheel builders would be jumping in with both feet to do this.
A hour to build and another hour for misc and overhead equals $300 per hour.
Build 10 wheelsets in 20 hours per week equals $3k per week or $150k per year part time.
John