Many of these shops are cheap because many people have tried and failed at these addresses.
Today we go strolling in city centres when there is no traffic, ie on Sunday when the shops are closed. I believe the age of passing trade is coming to an end.
My approach would be to set up a website, or even sell your art on
www.ricardo.ch If you are unsuccessful there is no charge.
Another point is that many restaurants and hotels display art for sale. What better way to sell a painting than to have somebody sit in front of it for 30 minutes? I do think the picture frame is equally important.
These ventures will cost you very little, and you would remain in control.
Do you know about the Kunstsupermarkt in Solothurn in November and December?
http://kunstsupermarkt.ch/~rothus/default.htm
.