The problem is strictly within the KBB value vs. how much people are willing to pay. If some one is selling their NSX for more than book value and people are still willing to pay for it, yes, it will go for more than $25k. That's how the market works. Earlier NSXs at the moment, is in a seller's market, the later NSX has a buyer's market.
Eventually, the market will have an adjustment simply because you can't have a 2005 selling at the same price as a 1991, and I believe the 2005 eventually will drop down to $30 to $40k range.
I have seen many early NA1 going for less than $25k, in fact, there was one last year sold for $17k, needed some work, but not $8k worth of work.