Amazon has the Rubbermaid LunchBlox Insulated Lunch Bag, Medium, Black Etch for $9.04. Free shipping with Prime.
https://www.amazon.com/Rubbermaid…00
(Note the medium size is cheaper than the small size.)
Excellent reviews: overall 4.4 / 5 star rating from 1,750+ reviewers.
This lunchbag is also available at Walmart for $9.04 with free store pick-up.