I bought these vinyl seats for my 1979 Alfa Romeo Sprint Veloce in 2002 on eBay for $99. They had no rips or tears but looked dirty.
At the local automotive paint store I bought three cans of SEM Colorcoat 15093, Light Buckskin for about $10/can (13 oz). There were also SEM cleaners and surface prep. The guy at the store said just to use lacquer thinner, which I did. Two and half cans later they looked OK. I painted them in July 2002 and they have held up very well – no cracking or chipping.
Colorcoat seems to be more of a flexible paint, than a dye. The driver’s seat shows dirt but it cleans off with Simple Green. The apparent unevenness in the color in the photo is due to the lighting, rather than the application of the paint.