Odd you should say that - I just read that also, and have been googling furiously since. Only found it available in one place so far in the UK, and frankly, it's rather expensive. The alternative seems to be a TSO connector product, stocked by Axminster at £75 for a $50 product (as a professional importer for 25 years, I know the perils of cross border price comparisons, but even so, this seems a decent markup). Two reviews on Axminster for this, one positive, one middling.
Have to say, if the Betterley was priced more reasonably, I'd have pushed the button (it's sold at £125).
ETA - perhaps a UK firm specialising in aluminium would fancy making their own version........Benchdogs, if you're reading this?