Just buy one of those 15 dollar insulated cooler bags, stuff it in your bin, add blue ice and walah. And as a bonus, it's mobile!

 

If anyone wants to make their own bin cooler, I have an engineering background and will help you out. Just PM me. I can even tell you how to set up a 12V powered thermo-electric cooler to chill it without ice. Ballpark for materials is $20-$50 per bin, with the upper end including the TEC cooler.

I'm not sure but I think the pics posted are the stock bins with all the carpeting removed.

 

No way. The stock bins have a two-part lid that screws together, and the bottom of the well is a soft, unstructured "bag" of carpeting. If you took off all the carpeting from inside the stock bin, you'd see right through to the steel floorpan. Also from the photos of the OPs bins, you can see the fiberglass strands in the underside of the lid. This must be an aftermarket piece.

 

I meant I thought (IIRC) I saw hard plastic after removing that cloth bag, not the chasis. But good point on the fiberglass. Probably aftermarket then.