Semi C&V Related, I went to the first napa bike festival today (gotta say it was nice and relaxed/fun), it was my girlfriend my friend and myself. My friend wanted to upgrade his rear derailer for his proflex, after we'd already hit most of the booths with bins of goodies etc.. so we went back through and didn't find much, I think the best was a 300lx RD before we stumbled across a vendor selling these

It's plastic.. like 90% it has a spring, the backplate of the arm itself is also metal (and small), there's pop rivets it looks like and a mounting bolt, and a nut built in for the cable tension screw.. and of course the screws themselves.. but otherwise not a drop of metal... WTF were they thinking? the vendor claims they last surprisingly long, I found this doubtul but I bought one as a conversation piece not for use. My friend ended up going back later after I bought mine to get one to find out just how long they actually last.. I'm praying for his bike.

So why did they do this? I know simplex liked plastic too, but this much? what's the reasoning besides CHEAP?