[Macbow]

I make my own tapered shafts - 11/32 with the last 10 inches tapered to 5/16. I used to use the Rogue River Archery tapered shafts but even though I was getting them from the USA it was still working out pretty expensive. I bought the Woodchuck taper plane from the USA ($125 including shipping) and found it very easy to use for making tapered or barrelled shafts from standard parallel shafts. I set it up initially by putting one of my RRA shafts on the jig as a template. It takes about 10 minutes per shaft then a quick finish with sandpaper. I lose approx 2lbs of spine from a 10" taper. You just have to set the plane to make very thin shavings - too deep and it rips chunks out the the grain.
I saw another method on a US forum using two pieces of angle iron screwed into a board. Put a previously tapered shaft on the board between the pieces of 90 degree angled metal to use as a template then screw the metal plates into the board - basically you get a metal channel 11/32 at one end and 5/16 at the other. At the 5/16 end you put a stop so he shaft can only go so far. Using double sided carpet tape stick heavy duty sandpaper to the angle iron. Glue a field point on one end, stick it in a drill chuck and spin the shaft through the metal channel to get a pile of sawdust and a tapered shaft. Never tried it myself but apparently it works fine.
However, if you can get tapered shafts for a mere 50 pence more than the standard shaft I wouldn't bother making my own!