My vintage JBLs vs new B&W, PMC etc.

My system:  Bryston BP-26 pre-amp, McIntosh MCD500 cdp, Conrad Johnson MV-60SE with JBL 4312s or Bryston 4B-SST2 with JBL L150As.  Audioquest Coral interconnects and nothing special speaker cable.

The dilema:  I keep thinking the next set up will involve a $peaker up grade.  I go to the dealer and listen to high end demos and then return home only to find I still find my JBLs just as good.  To be fair, both pairs of my JBLs are in near pristine condition.  I compared my 150As to PMC PB1s and while I really liked the PMCs, I eventually sold them because I could not discern any real improvement over my 30yr old 150As.  I also sold my Kimber 8TCs with the PMCs for the same reason.  My listening room is about 30 wide by 20 deep.

I recognize that you can't just walk out and buy 30+ year old speakers in mint condition, I was very lucky to find these, but I find it interesting that I can't seem to find speakers which are significantly better sounding for less than the price of a new car.  Is it just me or is there something I'm missing.