TSC can also order parts too.
When I wanted my gull wing tool box, they didn't have any but they were able to order one & a week later it was there.
You have to find the right person to talk to though, some of them don't know their butt from a hole in the ground, but the guy I got was really helpful, he even said he could get it in black instead of bright aluminum.
If you have any metal recycling places nearby, give them a look too. My uncle bought 4 or 5 random aluminum truck boxes for as little as $10 each. They had a few scrapes & dings, but he cut 'em up for the diamond plate to put on a car hauler he was building.