yes, twice. antique day bed was about £1000, and our water-damaged expensive sofa (£3K new) was £1.5K to re-cover in the same wool fabric. So it does cost a lot, but if the sofa frame is high quality or antique then it is worth it. if the basic frame is cheap, then don't bother.
Thanks Parietal - sounds as though it might be worth doing, then.
The sofa was second hand to us, so I've no idea if it's a very good quality frame or not, although I think it might be. It's in generally good condition, just has wrecked cushion covers thanks to a sustained attack by a kitten!
If it's just new cushion covers you need that should be way less - couple of hundred depending on the fabric. And if you go loose covers made from ikea fabric (v durable) then you are only looking at £6-10 per metre for the fabric. Other upholstery fabric can cost anything from 20-150 quid a metre.
Lots of people do upholstery in a very low key "from home" way so try to use one of them (I use mums at school - ask around) and they will be cheaper than someone who advertises and has expensive high st premises etc