Back in the '70s and '80s, many local used car lots would use a local trim shop to "used-car-ize) the interior of some of their cars. Nothing like an OEM job, though. Just took a sheet of vinyl (reasonably color matched), basically throw it over the front, wrap it over the top, and put some side pieces in to hold everything together. Usually looked pretty decent for what it was, but that was usually on a 4-dr bench seat car. BUT for a little bit more money, they could have had a nicer-looking, more correct looking, repair job done.
With regard to the JCWhitney reference, WalMart usually has a decent selection of various slip-on seat covers for a variety of seat configurations. Several brands, too. PLUS some of the clear vinyl floor mats (just not as wide as the old floor pan foot wells).
CBODY67