Upholstery isn't cheap but it is great value. Prices will always depend on the style and condition of the furniture and the fabric chosen so I need to see all furniture to give an accurate quote.
As a guideline, here are some average prices from recent projects - all are excluding fabric.
Modern Upholstery - Post 1950 - constructed with foam
Dining Chair - £30
Armchair - £350
3 Seat Sofa - £600
Traditional Upholstery - Pre 1950 - constructed with fibre/horsehair
Dining Chair - £50
Armchair - £600
3 Seat Sofa - £900