Materials

Hi, I have a one year subscription to this esewing workshop and I bought already a sewing machine and serger. As a beginer I want to start sawing simple things. As of now I want to make my own pillow cases and bed sheets. I need help as to where can I buy good textile for this project? I want cotton, at least 400 count thread and at least 72 inches width. The textile stores I visited  have only 45 to 60 inches width. I hope  you could help me. Thanks!