SB look into WW Grainger Supply
as they carry a large inventory of barbed nipples like this in a variety of sizes for air cylinders and other industrial equipment and usually have local supply outlets near major cities... I buy most everything there...
Grainger Item # 4A491
Price (ea.) $1.47
Mfr. Model # 4A491
This is the full category of 5 pages:
Sorry though I think 1/4" is the smallest right angle barbed fittings carried in stock. Generally in models we use standard brass tube for 1/8" outlets and solder around the inlet. There are quick connect brass fittings 3/16" and 1/8" ID neoprene tubing with O rings in them and plastic slip collars but they are pricey and would probably be prone to melting and leakage if soldered in place or you tried to use with the much softer clear tubing for fuel as the OD sized would not be the same as neoprene air/vacuum tubing.
Here is a 1/4"-1/8" barbed fitting but it is 60 day order:
You can see smaller fittings here:
This is one with a brass collar:
Grainger Item # 2ZKR1
Price (ea.) $25.90
Mfr. Model # 1869X4X6S