Where can I purchase an F-Bayonet lens mount for my Nikon Lens?

I've tried Amazon - they won't ship to where I live (Canada). I've been looking for weeks where to find one of these on the internet. It's like a $5 plastic ring, how hard could it possibly be? Obviously too hard for me.

Thanks in advance for suggestions!

Added (1). Sorry - not really an expert on what's wrong. All I know is that there's a plastic ring that connects my lens to the camera body. I'm told it's an F-mount or F-bayonet - I really don't know. But I found the part on Amazon at one point for like $5 a ring. I need a replacement mount for a DX AF-S 18-105mm 3.5 - 5.6G lens.

I'm not entirely sure what you're asking, the F-mount IS for Nikon.

Although it's been modified since its introduction with the Nikon F SLR in 1957, (Auto-indexing, electronic contacts, autofocus capability) the dimensions and back focus are still the same.

Http://bocaphoto.com/products/new/nikon/nikonparts.htm

scroll to the bottom of the page, but it's on back order.