Chainreaction cycles has some cube bolts for sale. If they're not the right ones, you could try ordering them from the Cube store in Durham or a cube dealer. Failing all that if you have a good LBS, take the frame to them, they might have something that fits.
hey man chainreactions don't do the set. you have to get on to cube them selfs. i had the same issue cost me 80E for the hole bikes pivot bolt set, can't just buy the one single bolt which was annoying but good to have spares.