We had a thread about those curtain rods not too long ago. I'm not sure which exact ones U-haul
used, but I'm talking about the rods that are like long springs coated in white vinyl, and that have little eyes on the ends of the springs that fit onto clips on the wall.
I found these at a Wal-Mart in Ontario, in with the rest of the house curtain rods, and they were called "curtain wires." They were just one of the generic brands that all the other lightweight curtain rods and supplies were.
I passed them up thinking "Why haul them back over the border when I can get them at Wal-Mart?"
Then I found that --- in my hunting anyway --- they are not available at any US Wal-Marts or anywhere else I've happened to look. I haven't search exhaustively (or on the web), but I have looked at a lot of Wal-Marts, Targets, Jo-Ann Fabrics, and the like. No curtain wires!
A number of folks piped in to mention that they had found them at various stores, but I noticed these people were all posting from ... Canada.
If you have a friend in Canada....