Plastic seat covers from a local reupholster shop might be an easy and inexpensive option.
Might be able to sell your old leather seat covers and recover some of your expense.
Good chance to do something custom to fit your taste.
Interesting how people used to replace their cheep plastic seat covers with natural leather. The plastic was evil because it was made from petrochemicals, and the leather was considered more eco, as the leather otherwise was going to waste when the cow was butchered for meat.
Best for the environment might be seatcovers from a renewable resource like cotton or hemp.