Well, I can't really answer for sure, but here are a few ideas....
Supply/Demand - As demand shrinks (fewer pilots), a/c mfrs need to recover costs over a smaller sales base, therefore prices rise. Fewer units, higher prices, same level of profits.
Type of new pilots - as the various anti-Cirrus driver threads imply, perhaps the average new pilot today is financially better-off, therefore able and willing to spend more for a plane. Fewer new pilots, but with more $$$ to spend, = higher market-clearing price for supply.
There are other factors -- I don't know what the overall a/c registry numbers are doing, but older planes drop off the registry every day, and new construction will never match the numbers of the heyday of aviation. Thus, supply shrinks, and if it shrinks faster than demand, prices will rise. That argument is contradicted by the obvious sag in older a/c (pre-1996) prices. That in turn may be more due to fuel prices and greater price elasticity of demand in the lower-end of the a/c market.
Stop me before I bore myself.