heres the reply from my dad:

they are called zip walls, I got them at Lincoln contractors supply in k town, since then I have seen them cheaper ( they are expensive) most times we aren't using them if you'd like to borrow them I have no problem

I want to think they are about 170 per pair


p.s. by k-town he means the city just south of me. look around on the net for that name, if its a tool worth its salt though, toolcrib will have it.