I can't find anywhere in Liverpool or Chester but a bit of websearching has suggested that these might retailers might have what you want. (NB: The web details about these shops are all very sketchy. I can't guarantee that they all sell saris. Phone to discuss your requirements before travelling):
Shah Fashions,
602 Stockport Road, M13 0RQ.
0161 225 7113
Habib & Aziz Fashions,
8 Bury Old Road, M8 9JN.
0161 721 4959
Ashraf & Sons Ltd,
20-24 Chatley Street, M3 1HX.
0161 832 9682
Rahman Garments,
477 Cheetham Hill Road, M8 9LR.
0161 795 3514
Punjab Collections,
225 Wilmslow Road, M14 %AG
0161 256 4797
Chris