Are you stuck on those airframes? My dad and I are selling an Aztec. PM for details.

TT is not much of a factor as time since overhaul on engines and props. Be cautions of planes with time since top overhaul, could be an indication of a previous mx issue. The whole buying process can be quick or drawn out. Usually a day to look over the log books and a test flight. Then you will want to have a pre buy inspection done, preferably at a mechanic of your choice. If you take it to someone that is friends with the seller, they could avoid and not mention some things. After the pre buy, get the finances in order and you are pretty much done. You could do all this in a few days if you have the time to do it. Another factor to look at is insurance costs for each airframe, as some will be higher than others. Our aztec has a G530 in it and it is pretty user friendly once you get the hang of it. The 4 and 530 are nice pieces of equipment that can do a lot. What kind of flights will you be using this for? Load and range etc? Also, be cautions of buying a plane from the south around FL due to corrosion issues. I'm sure there are more people that will chime in that have bought more planes than me and have more useful info too. Good luck