Why can't I buy separate power line adapter extenders when I already have the kit? I can only find the bottom of the range av 600's on there own. I want an av 1000 or 1200 to extend my network but don

I have the kit, why can't I find extenders sold separately apart from the bottom of the range av 600? I don't want to buy loads of kits with extra senders that I only need one of by the router.