Does anyone know if someone sells paint in quarts for changing the color of seats or just in spray can?

You can get SEM vinyl die by the spray can, pint or quart. Check with a local paint jobber.

I've used the SEM dye in the spray cans to re-dye my door panels and had really good results. But never tried to do a whole seat.
I'm going to give it a try though, I've swapped my blue front bench for black buckets so I'm going to try the spray cans for dyeing my back seat black.
I'm thinking that you might get better coverage if you go the quarts and sprayed it with a real spray gun.

Post a before and after pic if you can, and good luck

SEM dye? funny, i want to change my black bench to b7 blue.

http://semproducts.com/index.php/product...coat-chip-card/

I'm sure it's possible based on the number of colors they have available. You are probably into a custom mix if you need an exact match. The paint store by me can custom mix pretty much any color.

Another (expensive) option:
https://www.yearone.com/Product/DisplayProduct/249395