Originally Posted by oldschool hero
Try McMaster Carr They will sell small quantities where the others don't.
McMaster Carr does not sell upholstery supplies. There are three places on line that might sell in smaller quantities: Rochford Supply, Your Auto Trim, and Perfectfit McDonald. If you still have trouble finding things in small quantities, PM me.
As far as thread goes, you can use bonded nylon or bonded polyester in size 69, 92, or 138. (The higher the number the thicker the thread. Size 138 is twice as thick as size 69.) Both are equally strong, but polyester handles color fading, and UV protection a lot better than nylon. If what your sewing will be outside all the time, use polyester.