eBay is the best place to buy some... The MAS also maintains two sets for members to borrow, I have one set in Rowlett, and DalaiTom has the other set for people on the eastern side of the metroplex...
If you'd rather just buy your own bit(s) though, here's a place to get 'em off eBay:
http://tinyurl.com/2cnozm
You'll need to convert from mm to inches, and also keep in mind a 1" bulkhead requires a much larger hole, but you'll need to measure your actual bulkhead to know exactly how big, different bulkheads have different outer diameters, even among the same inner diameters...