If you DIY -
Upholstery - $260-360 (maybe cheaper if frnt and rear bench)
Foam for front seats(buckets) - $200 (not sure about front bench, don't think they make foam, rear foam is usually still good)
Hog Rings - $30
Fencing Pliers - $10
These would be the prices approx if you would purchase from an Aust. seller.
Sore fingers/incredible frustration - priceless.
You have to also consider that springs etc. may be broken and will need fixing, if so become friendly with an upholsterer, he will have some springs and clips to repair.
But if all goes well you could do it for $500..