Anthony,
I have an 18mm black NATO with bright hardware. You want it? PM/email me.
Lately I have been buying my NATOs from RMnilsen on ebay (that is his user name). Normally around $11-13 each and $1.50ish for shipping. Bill Mahoney is also a great guy to buy from and is a little more expensive for a single strap, but will make very good prices on bulk orders. He posts as 'Squinky' on several of the watch forums.
I have ordered three times from westcoastime.com, and every single time one of the straps in my order was the wrong color/size/style. He even sent me the wrong replacment strap once for a wrong strap that he shipped in my order. He has always been very nice, and very apologetic, but geez, every single order?!?! There is a short thread over on the Seiko/Citizen watch forum about other people having the same problem too.
Countycomm.com has all the Zulus, including the 'Navy Grey' that nobody else seems to be selling right now.
Danny