This is the type of clip that is included in the SD grip clip set, but they will end up costing $3 each.
Still for one tent they could be worth it, especially if you want to experiment with the placement of the clips, or have other uses for the 'grip clip' part.
But you can get the 'grip clip' part in bulk from these people:http://www.shelter-systems.com/gripclips/products.html
Their black size (20 for $25) is the same as what SD uses. This black light weight size has a slot that takes webbing (as with the SD product), but other grip clip sizes have two small holes that take a knoted string.
is a good source of hardware, but I don't see anything quite like what you want.