This one looks pretty clean, but no pictures of underside: https://www.ebay.com/itm/1971-Buick-Skylark/392043238947?hash=item5b47991623:g:~bkAAOSwqxRa5xlw
One picture of the underside if you scroll through the pictures here: http://topclassiccarsforsale.com/buick/280207-1971-buick-skylark-custom.html Looks very similar to another car that sold in 2015: http://topclassiccarsforsale.com/buick/41138-1971-buick-skylark-custom-coupe.html This sold for $9,500 then. VIN is different and this one was missing the Skylark emblem on the grill and has a picture of the car from behind showing some of the undercarriage.