It was $3400 a month at Chinook for a kiosk in 2011 (busy season leading to Christmas).
As of last weekend, there is a vacant kiosk at Cross Iron adjacent to the food court. Maybe you could get a deal so it isn't sitting empty.
But realistically, how many man-children are you going to find to offset rental costs It's a pretty niche idea.
Stick to the suggestions of the flea markets, or try out the farmers market. Find a way to get the word out and test the waters.