AFAIK, anything fitted to a certified aircraft requires an STC or TSO or came with the aircraft. I'm not even sure you could legally fit the McFarlane parts without a LAME doing it (you can remove seats legally).
Hence using anything from super cheap auto leaves you open to criminal prosecution if you are ramp checked by CASA.
To put that another way, you need a Cessna certified cargo net (it's in the c172 POH) to restrain your gear backed up by certified tie down ratchets. It shouldn't cost more than your entire camping trip budget even if you can find them.