Trailer parts - NOR

Does anyone have any experience with or know where I can get 2nd hand trailer parts NOR ?. Looking at making a bolt on wheel carrier for my trailer to do beach launching. Also looking at a draw bar extension of some sorts, nothing complicated and will be very simple as it's not going to be used that often.

I know I can buy brand new, but I enjoy making up my own gear from excess I have lying around in the shed.

All I really need is a trailer axle to cut up that has hub, bearings and seals, only need one side unless I make two. My spare wheel is one of those multi fitting types that can accommodate must hubs, so what type of axle should not pose too much of a problem.