What kind of loads you looking for?
You could buy some small dia pipe from the hardware store. Some I-beams, maybe would look nice if they were weathered and some numbers spray painted on in some ugly bright orange. I think Ric sells some large crates, boxes and pallets, plus some other stuff.
This link should take you there. Hope this helps.
Garden Trucking Cargo page
Oh and I too think this list would be good squeezed down and made sticky...