Wow there is a huge range out there these days i was getting lost in all the choice myself. I did find this little site though that seems to focus on
folding electric bikes. Seems like a cheaper range of brands reviewed. If anything it may help you narrow down the choices,
It did have some reviews that meet your requirements (The 20" wheel size, basket, step through frame, suspension). Not sure if you could test ride one though would need to check if your local bike shop stocks any of them.