Ordering one box of clips per single roll of the screen will almost always suffice. On average, 50 to 75 are needed per 100 linear feet, but no two systems are the same. We sell the two products separately, and not as a kit, to allow you to order precisely what you need.
Long straight runs require fewer clips, while corners require more. The type of racking used can make a difference as well, most often requiring fewer, other times requiring more. An experienced installer, looking at the schematic, can count almost exactly the number of clips needed on a particular system.