Shift from gas heaters to electric?

[Terra Ma]

every winter, tenants want me to replace their existing wall gas heaters, and I have. However, CA is shifting to electric (not sure re the law here) and wall heaters are like $800 at Home Depot. Does anyone have experience with electric plug in heaters? Is that legally allowed? I see a couple on Amazon that are like $150 from heat storm that claim to be able to heat up 300-500 sq ft. Any options and opinions on ripping out existing wall heaters are welcome.