“Even if you deal with the tubing supply chain and consumer retail price tolerance, there is no supply chain here for the cables, shifters, crank sets, chains, saddles, and every other part. It would take decades to set all of this up, but you would first have to get consumers to the point where they will pay $1,800 for the bike that they could get for $400.”
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.