Nice find.
If the floors, rocker panels & the underbody X-brace are in decent condition as the body appears to be, I'd say go for it!
Also check the center crossbrace of the trunk floor, & the leading-edge rail (frame) of the front trunklid (especially near the hinges), both prime spots for rust damage.
The pics are a bit blurry, but places I see worthy of a closer look are the center section of the driver-side lower rocker panel (under the door), the lower rear corner of the passenger-side rocker panel (just in front of the rear wheel) & the upper rear corner of the driver-side rear fender (the part that surrounds the outer corner of the taillight). Might be damage, might just be dirt/leaves/lighting/bad photos.
Judging by the just-barely-visible alloy oil pan cooling fins seen in the photo of the rear, it looks like the car might already have had an "upgrade" from the original early 817cc engine to a later 903cc unit - a plus in your favor. Check the driver-side of the engine block (above/forward of the oil dipstick) for either a "100G" (817cc) or "100GBC" (903cc) number/letter casting.
IMHO, $800 is the perfect price for this car, with a little wiggle-room depending on body damage/rust. If everything checks out ok, an offer of $650-$700 would probably get you the car with a bit left in your pocket for gas/food &/or truck/trailer/dolly rental (if needed). :italia: