It could be a lack of inventory to trade upóassuming that is what most sellers would do.
A decent dash 10 690B with good times will trade in the high 9ís or higher, but an equivalent airframe with better range and speed will likely mean turbofan territory at obscene prices. Plus insurance is hard on transition pilots.
Looking back to 2019 at Eagle Creeks price list shows some interesting pricing.
The 1000ís were high even back then.
N730MV listed at $1,595,000
All the dash 10 690A/Bs were asking 700,00 and up.
N690PT was the lowest, N690HF was the highest.
YV1173, A Venezuelan 900Ėwas asking 895,000 back then.
Scott at Byerly mentioned a really nice 690-10-stec3100 bird sold above 1.2.
Wonder if the market is getting softer now.