They sell them at the Bunnings store near me Wayne, you want me to pick a couple up for you? Last lot I bought (3/8", that's close to 10mm, Bunnings don't sell metric cobalt drills) cost about 17 bucks each.
I say you'll need a couple because you'll bugger them pretty quickly drilling a 750 disc, and I hope you know how to re-sharpen them........... Have you got a drill press that'll drill
real slow? Also, the best lubricant (believe it or not) is straight dishwashing liquid!
Don't try to use a hand (electric) drill, you'll only bugger it.