Khuldun,
How much did you pay for you car. You really paid honestly and I'm sure you really like your car. Why do you want to spend all that money and not be seated on stock seats ? (these days I think all cars are coming with fabric/leather seats, atleast the metallic paint variants)
My philosophy is that seat covers come in when you want to sell the car and the seats are torn etc. Till that time, one needs to seat his behind & enjoy the original seats, rather than covers.
If you are concerned with cleaning the seats because kids might ruin them, all it takes is a warmly damp cloth to wipe clean them, even sweat marks. Vaccum them once a month in summers or if dusty conditions persist.