Good luck with that no one in my area stocks much of it, your best bet is to look for a local hobby store (
RC cars / Trains that sort of thing).
I keep meaning to place an order with these guys, they seem to have a fair amount in stock but I have no idea what the service is like.
http://www.modelsforsale.com/catalog/index.php?cPath=8_89999134
You can search that site by part number so go to the evergreen site first
http://www.evergreenscalemodels.com and look up what you want. Evergreen put all the dimensions, including internal dimensions, of their items on the site, so you can make sure rods will fit into tubes etc etc.