Homemade high-speed spindles/speed multiplier. What bearings to use?

Hi All,

I'm looking at making my own belt/pulley based spindle speed multiplier
for my CNC mill, and was wondering what bearings I should be using? The
milling cutter itself will be quite small (1/8" or 3mm), and high-speed
so it doesn't need to be too-beefy.. the reason I ask is that angular
contact bearings are quite a bit larger than regular sealed-race
ballbearings - and more expensive, I'm not sure though if the price
warrants the extra expenditure - a ballbearing based spindle would be
more streamline and easier to make...

I've seen some fantastic pages of people (on this list) who've made
their own fantastic spindles - so this is why I ask. :)
I intend to "open source" the design when it's done, and post all plans,
drawings, 3D models, construction pics, and a how-to guide on my website....

Thanks for any advice,
Regards,
Abby
(http://www.silverkatt.co.uk)