Missing log books should not be red flag. Do your research is all. Mine is missing its first log book, no problem did research, an honest loss. Have 2nd and making 3rd now.
If you like the plane, read what logs there are and write down the sellers story, check aircraft with a finer tooth-comb than normal and make sure it all matches.
Most of what I seen was older nav/comms will cost later, make sure the avionics and mods have orig, paper work and is correct and COMPLETE(all STC etc), if not work away unless you already know what the new paperwork will cost.
EG:
autogas STC paper on hand and filled with FAA. NO.. $200
Avionics 337's, flight manuals sups paper on hand and filled with FAA. No.. $400-$2000.
Number one rule NEVER fall in love with the plane. (just give me $6000 same thing/result). Number two is ALL WAYs pre-buy inspection, short annual inspection good idea spend the $800.
