I use these http://www.irwin.com/tools/drill-bit...tep-drill-sets or http://www.mytoolstore.com/klein/59001.html or http://www.google.com/#q=uni+bits&hl...w=1603&bih=749 , I've had pretty good luck with them.

I have drilled roughly 30 holes in 1/8" stainless with a 1/2" Irwin unibit and still had enough bite for more. Check unibit on the bay and you'll find some great deals. Dont forget to use a little lubricant, that always helps to. Spray it down with some contact cleaner or whipe it down with some dykem dye remover before welding the bungs on