If you can find a used Sturmey Archer S3X hub, a Sturmey Archer 3 or 5-speed hub, or a Shimano Nexus 3-speed hub; we can help you set up a strong multi-speed transmission system that drives the left side of the rear wheel.
SBP is shutting down and selling off its inventory. With those eBay/Amazon shift kits you're going to need the SBP upgraded bearing or you're going to be doing the Walk Of Shame. That's why they are being sold so cheaply.
If one could get Staton Inc to build them a triple chainring shift kit exactly like mine it'd cost over $400.