Back seat covers or hammocks

[r-kid]

Can anyone recommend a large back seat cover that doesn't cost a fortune. All the normal ones from Amazon, petsathome, etc. are not large enough to cover the back of my car.

The largest I've found is this:
http://www.orvis.co.uk/p/deluxe-microfibre-car-ham...

but I'm reticent to pay the £150 for it.

So any recommendations would be useful.

Thanks