I wanted to try a heated jacket but did not want to pay much in case I did not like it. 
I bought one of these  www.aliexpress.com/item/1005005568690222...atewayAdapt=Msite2Pc
from Aliexpress for about $27.00 delivered.It runs off usb either from my bike or a usb adaptor for my Makita batteries. It is not hot but warm enough under a riding jacket to be very comfortable. Quite impressed really for $27.00, The sizes are Asian though.I bought an xxl and it is just big enough.