Scrap aluminum has dropped 25% this year - and the salvage people want clean aluminum, the vinyl covered liners have a steep deduct, any vulkem or other caulk residue puts that chunk in another stack, etc. etc... So its anywhere from 20¢ to 50¢ a pound as of 7/25/12 - and there is less of it than one would think. if our 0.032" sheet is around 0.45 pounds per square foot the 27' trailer may have $180 in sheet stock on it and much less of the formed ribs and channel. Iron scrap is 4¢ a pound w/ 500 pound minimum so you'd be lucky to get $60 clear there.
If you wanted to snag it your salvage value would come from complete window assemblies, entrance door, utility hatches, vintage stainless water heater door and a few other things like door light, FW filler port, external 120VAC cover, bumper and trunk lid. If you are doing internet sales your crating/box charges will be steep.
To earn more than 25¢ an hour for your labor you'd have to get the trailer near-free, free or be paid to haul it away