Here's the thread where I bemoaned the same issue and finally decided to make my own. The posts detailing the work are about half way down.
http://www.thehighroad.org/showthread.php?t=718779&highlight=made+front+sights+1860
My machine shop isn't set up yet so I went with using hand tools for the whole job. And really it wasn't that tough to do with a basic hacksaw and some files And if you have anything more than that you're gold.
The KEY is to use a dial or digital caliper and use it OFTEN! When going for a basic friction fit the old rule of "measure twice, cut once" most certainly applies.
For removing the bulk of the material a fine cut file works great. Once it's down to where you're ALMOST there I switch to polishing the sides with an oil stone until I achieve the nice tap in fit.
One trick to making this easier to gauge is to lightly chamfer the edges of the round woodruffe key like base so it self guides and wants to slip in. When you stone it down that last .001 for the right fit you should be able to push it in by hand just a little before it bites in too much. A very light chamfer from the stone will aid this.
The tapering of the upper blade is more for looks. But if you start too wide you can use the extra width for correcting the windage to some extent.
Note that you're doing ALL of this with handtools and working with about a dime worth of material. So jump in and try it even if you normally consider yourself a bit of a klutz at metal working. If you mess it up what's the risk? Another dime's worth of material and some of your time. I don't want to see anyone posting that it's too complicated. Failure IS an option in this case. A harmless learning option that raises your skill level in preparation for the next try.
For those that might be totally new to hand tools in general and files in particular remember that a file is like a really wide saw blade. And like any saw blade you want to lift off the pressure on the return pulling stroke and push down on the pushing cut stroke. It isn't a metal version of sandpaper.