As with alot of jobs the part is relatively cheap but it takes alot of labour, I had one done about 6 years ago ( this is a common rust area on these cars but once done its good for another 10 years) and as I remember the part was about £70 and they billed 3 hours labour so I would say a good £250 minimum but they are pretty bullet proof cars so if the rest is good it may be worth the cost.