As Bob says, they are indeed actively making them now and more importantly they are making them better than ever.
The current all-in upgrades use little more than the case and heat sinks from the old amps. Send them a non-working amp....it doesn’t matter. The end result will be stunning. They have completely new boards, use larger low-noise toroidal transformers, and virtually all new parts that they have found make the most sonic improvements. Ask about the benefits of their Gravity Base option. The case can be powder coated, copper clad if desired, and finished per your choice. They will have a new faceplate made to match your aesthetic preferences if you wish.
I saw that eBay DNA-0.5 amp and it would have been a good amp for somebody who wanted something better than stock but didn’t want to sink a lot of money in it or go through the upgrade process. However, their upgrades have come a long way in the 22 years since 1999 so for me the price was too steep considering the age. Nonetheless, I suspect it can give the new owner years of musical enjoyment.