I recently bought a job lot of .33mm carbide drill bits. I had an idea they would be great for pre-drilling for re-pivots and they have more than proved their worth. I did a .6mm pivot on a tiny fly last week and carbide drills make the job so easy. I can now pre drill with one of these and then finish the hole using a standard steel spade drill. I have found that if you buy boxes of ten of the same size they come quite cheap. Just dont use too much pressure and they cut so well it makes them worth their weight in gold when you come up against a hard arbor and your steel drill bit is just "polishing" the start of a hole.
Here is a link to some in China but just type in carbide drill bits and you will see plenty.
Paul.