I purchased my drill and bulkhead from www.glass-holes.com. I should be receiving them in the next day or two. I have read a lot good reviews about them, never read anything negative.
You can buy bulkhead fitting at any plumbing supply store, not hardware store, but plumbing supply store. Or... you can do as stated before and order them on-line.
check in the sticky section for dilling tanks. Chompers wrote a great article on it.