Ebay is good for large quantities of curtain material, mishap. There are rolls of fabric that you can buy at nominal prices, or lots of examples of materials for £3.99 a metre, and the quality is fine.
My son and fiancée recently bought matching curtains for the whole house in the Boundary Mill sale. The ones they got were Rectella - lined, beautiful fabric, original cost for floor length drapes were £200 a pair, knocked down to £67, then a further 10% off at the checkout and they got five pairs for about £280. They had tab tops but one set were for a track, so I cut the tab tops off, sewed Ruflette on and made two pairs of tie backs for their downstairs curtains. There were plenty of unlined curtains at a fraction of the price, too, and you can get bargains all year round. When we checked the cost of having the same curtains made, they would have been £1,500.
If you buy fabric off Ebay, you can get tracks, hooks and Ruflette very cheap on there, too.