Mcmaster has them in 1/8, 1/4, 3/8, and 1/2.  But no 3/16".  Durn!  BTW, they call them supported 45 degree brass flared tube fittings.  Never heard them called that before.  They were inverted flares ever since I was a pup.
The part number for the complete pipe & nuts assembly is 277213, listed as not available.  Try some of our guys that have NOS parts in stock.