I used Kejal's on Laxmi Road for Window curtain cloth. They have quite a good collection and in Monsoon's they also have a SALE where they have good discounts for some of their material. You could check that out.

Curtain shops in Aundh (the last I know) are outrageously priced.

Fab India has ready made curtains as well - quite a few of them reasonably priced. They now have an outlet in Ishanya Mall which is quite well stocked. Shoppers Stops also has readymade curtains - buy those only when they are on Discount.

Checkout Prime Furnishings on Karve Road (opp Alurkar Music House/Swapna Nagri).

I forget the name, but we found a store very near Pimpri station very good in terms of both the collection and the price. Will add back the name if I recollect it later.

Shah Deepchand Dharamchand on Kelkar road, near Kesariwada has a very wide variety of curtains. There is also another good shop called Bosco furnishings near Shanipar.