You'd think it would be worth something but everyone is scared off by the high engine time. People have strange priorities.
Yup! An airframe well inspected and known to be in good condition is priority one! And a high time engine... well, in good working order, means it's a good engine! Keep it well maintained, and keep using it frequently and with care, and it will go well beyond its TBO! I ran my O-200 through to 3600 hours, and it still really did not need to be zero'd when I took it apart!
The PA-28 wing structure inspection requirements are a valid concern, as they were back in the late 80's when the first version of the AD was issued. Unfortunately (as I discovered myself by calling Piper tech support) Piper is not entirely enthusiastic about supporting their legacy airplanes through difficult primary structure concerns. With a parts supply, the "industry" is entirely able to keep the fleet in good working order. The challenge is that PA-28 spars are not so easy to come by. Thus, buying a whole, known good second airframe is not a wild idea, if the parts you need are not available individually. We went through this with C 210 spar carrythroughs as well....