I suspect things like that are, for want of a better term, "factory seconds", either under or over the table.
In other words- and this is mostly speculation, mind- perhaps the manufacturer made more than the contract called for, and so they sold the rest off as surplus.
Or the manufacturer was contracted to make them, but the contract was pulled/voided or the contractor went out of business before delivery. So the production run is being sold for whatever they can get out of it to recoup their losses.
Or, as has happened more than a few times, a company designs a piece, and contracts to a manufacturer to make it. Said manufacturer then produces it, sells part of the run to the contractor, and sells more on the side to make even more profit.
Or they're unsold leftovers that are just being fire-saled away simply to keep from having to throw them away.
Keep in mind that Harbor Freight got it's start buying up containers of essentially abandoned product that for one reason or another got left at the loading docks. (It's not unheard of for a company to go bankrupt and close while there's still containers of product on the ships and on the way.)
So it's possible somebody got a surplus containerload of these, and are just flipping them for a few fast bucks.
And finally, keep in mind that everything in that chassis is off-the-shelf, and massively cutthroat-competitively produced. Basically that thing is a faceplate (no different from millions of TV remotes and non-smart cell phones) a CD drive (as are installed in hundreds of millions of computers) a small memory card (which can be had for pennies per gig these days) and a controller board (again, same as any number of portable MP3 players, cell phones, what have you.)
The slide-out chassis was probably made by the millions by a high-capacity sheetmetal shop, the plastic parts were produced by the millions, and the internal pieces were made by the hundreds of millions.