Suppliers is one thing, its whether they get used int the stores.
Check out an outfit called Checkpoint, they do RFID stuff for big retail chanins and there is a link with Supercarts stuff. I found it via Google looking for RFID and Supercart, you cant find it if you check the checkpoint website.
This isnt the Checkpoint that produces firewall software by the way.
Odd. There are other companies making plastic carts as well. Supercart have orders in Europe and SA, and Walmart are interested, but its early days.
Good luck.