Ascension Battlecruiser convoy

A bit of a mystery, the Ascension-class cruisers are sold by a black market outfit somewhere within the lawless Empire of Many Suns. While the ships are in pristine condition, it is clear to many that the seller is not the manufacturer, as tests indicate these ships are thousands of years old.
It is clear that the seller is adding the weapon systems and doing some refurbishing, since many components and all of the weapons and control panels, computers and interfaces seem to be current technology.

Most experts believe that the sellers have found some cache, perhaps a lost shipyard in deep space, with a finite supply of these vessels and have decided the best way to make a fortune is to sell them one at a time.
If that's the case, then the cache was massive, as at least 20 of these ships have appeared in different hands over the last 30 years.
Another theory is that some ancient factory was found, and the supplier is simply using the materials that were left behind by the factory's creators, which is why the ships are made of old materials but seem to be in mint condition.
The battleships are fairly powerful, but rare and expensive, and the mysterious seller seems intent on only selling these ships to capable groups and individuals. The technology onboard, the incredible range of the vessels and the room given over to space and luxuries seem to indicate that they were originally designed as exploration vessels by some long lost and forgotten race.
The truth may never be known, and those who've attempted to find the source of these ships have either given up or have never been seen again.