I paid $70 for my Rich-E-Split box and the 20' stereo cable exactly a year ago back in April 2017. Works great for me. I generally split the Ric-O-Sound 4003 into my Fender Rumble 75 for the bridge treble pup and the neck bass pup into my Rumble 500C.
Years ago back in the 80's I made my own stereo split box and I would use my Peavey MKIV head/1820 cab for the neck bass pup and a marshall 100w superbass head through a 4x12 cab for the bridge treble pup. Thunderous stereo onstage sound. I have no buzz issues, maybe because Australian mains wiring is different here to the US and UK. I have no extra shielding in my Rickenbacker (also spelt correctly lol) 4003.