I haven’t seen a IM on eBay for a long time
That is very true about IM. Very few around as you have said, however BDK and SM both seem to have a high water mark for value. Anything above $6k just isn't moving (or getting any offers).
I remember at one time a few months ago on ebay there were 3 BDK's listed all in the $6k range - none of them sold at that price point (one is still being listed currently) and it took several attempts and a gradual price drop to $5500 or make an offer on the HUO one before it sold (outside of ebay so assume another price drop of at least a few hundred).
Sub 6k SM's don't sell well either.
Does IM fall into the same pricing category? Hard to say but I think once you get into the above $6k category for Stern on second hand models without the blingy bling added, punters are going to start turning their attention to NIB Pro models instead.
The blingy bling factor really is the key. As you said, you got $6k for an IJ with the added parts. Punters are now more than ever looking for added value on their pin puchases - the market explosion for after market mods reinforces this.
That specialwhenlit guy seems to be able to shift older model Sterns, but by God he has to pour a ton of aftermarket add on dollars into them to get them to sell.
It's a tough market for second hand Sterns and it won't get any easier as even popular base level units (Tron, SM et al) are starting to show up in the Euro containers quite regularly.