But I'm in Tokyo so I'm not worried about theft at all. It has an integrated lock on the back wheel and this blocks the handle too.
Tokyo is the best.
In China, they're about $300-$500 with lithium-ion battery. You can also get a kit (batteries, wheel with motor, wiring/etc) to convert a regular bike even more cheaply. The battery is the high-value part so you can take it out if you park outside overnight.