As others have said, these come up from time to time on eBay and if you prefer, the Nitto version (though it lacks "arms") can be had through a vendor like Ben's Cycle for ~$60. I ordered an old version (sans any bag - just a metal rack type thing) on eBay for around 25 and used PlastiDip to re-cover the part that goes over the stem. This holds an old TA bag for me, and does so dependably with moderate to heavy loads even. I have straps connecting the bag to my frame as well.
Velo Orange made murmurs of selling this, or a similar product, a few years ago. I'm not sure if they ever actually produced and sold them though -
The "Rackaleur".