Now, durability is a factor which should never be compromised with. Since you are paying quite an amount, make sure you double check on durability or else your hard earned money may go down the drains.
Another major criterion which should always be kept in mind is that seat covers should be heat and moisture resistant. If the covers are not such, long hours in the sun and occasional spills might actually spoil the whole effort. Choose wisely and give your car that glamorous appeal that it had never had before.