Probably the advent of the SDR into the mix hurt the SE-3 more than just about anything else.
That for sure, and the price was definitely getting out of hand. I doubt this was ever a high volume item, and I'm pretty sure they were all hand built, so a hefty labor component in each one. For a while, Rob stopped shipping them with the "bass boost" circuit because the inductor manufacturer either dropped the part or raised the price out of sight.
It is a very good box, though, if one can be found at a rational price. And with the AR feature (or mod) works well in AM roundtables. Doesn't require booting anything, and is unaffected by whatever happens in Windows update
Of course, there isn't very much good AM listening on the SWBC bands anymore anyway. Which is a shame. Not a complete wasteland, but the heyday of SWBC riches around every corner is long gone ..