Jim,
Have bought over 10 cars/trucks sight unseen over the years all with good luck.
Here's what I have them do:
Have them do a walk around video while using a (what I call a refrigerator magnet)
One that is very flexible and not strong at all.
Have them place it on all the areas that are known to have rust issues, if it falls off or doesn't stick walk from the car.
I must say from what you have shown here it doesn't look good to me especially for that kind of money.
Make sure you have him take pictures/video of the trunk around the wheel well area. Also floor pans under the car.
Good luck,Ron