I'd recommend finding a source locally because the parts are slightly different from different manufacturers so the holes may not quite line up even though the look the same. The is especially true of the hinges. The two parts used are called deck hinges and internal eyes. You can substitute with external eyes, of course. When I was searching previously, I got some advice that I ultimately followed. That was to let these parts may serve as weakest points on purpose.
Sourcing with stronger parts such as aluminum or some other metal may cause the fiberglass shell to become the weakest point. Instead of these parts breaking if snagged on a tree or because of some major stressor when deploying you might break the shell instead which wold be much more difficult to repair, even if it just strips the screws and the parts pop off. I don't know if FRP did this on purpose but it seems to make sense to me.
I ended up finding the right sized eyes and deck hinges at Bass Pro so I bought a handful of each and keep them in my truck. Living in the desert, combined with the extreme angle of the supports for my FP, I've replaced them many times. Ultimately, I bought some galvanized 1/2 inch conduit, cut it to length and flattened the ends at the appropriate angle, and drilled holes in the end. I haven't had a problem since them and it is rock solid. I have had to replace the deck hinges and they remain as the weak point in the system on purpose. They are much easier to replace than the eyes anyway.
I used a old folding table leg attachment and the clip part that the folded leg sets in for parts to attach the support leg to the top of Flippac . 
The pics show that the conduit flat-end and drilled , after I took these pictures I welded the end where flattened closed then grinded it smooth and dipped it in liquid rubber you use for tools and got new clip pin . It works great and haven't had any problems with it .
