I have the same nice Tumi hangers from an older "Alpha" bag that I don't use anymore. I don't see a way to purchase them separately, but there is a very similar product available from Bric's. Hopefully you can tell from looking in your own bag if such a product would fit. The Bric's product looks similar, but I think the Tumi one is nicer, with the clips, the rubberized metal, and a little more compact design. You might be able to purchase them directly from Tumi as a replacement part if you are so inclined.

You can find it on Amazon or cheaper on eBay. There are also "vintage" versions from Samsonite and an unknown brand available on eBay currently.