Try these, they manage most dremel style jobs and last ages. http://www.axminster.co.uk/axminster-diamond-30-piece-burr-set-prod21887/
I bought mine years back and have killed one of them grinding the threads out of the middle of an angle grinder nut (very hard steel) to make a headset spacer for a crap bike. There are loads of options on the Axminster site.
what i need it for is im porting a my rotary motor and i do already have one of these carbid burs to do most of the work i just need the stones and then the paper to blend it and smooth it out..