Siggy hardware was only on bags for a few seasons back in the day (maybe 2008, totally guessig here....) if your lucky you can scout out older RMs with it on Bonz and the bay, thats how I got mine! Good luck!
Really, I don't think of it as 'special hardware', but as something that RM did for a season (or two). There are TONS of bags that are pre-loved (but in really excellent condition) for sale on Bonz and eBay. With a bit of luck and stalking, I'm sure you'll find things that suit you, if that hardware is something you are really interested in.