currently on the look out for storage units....what to watch for???

i been seriously thinking on what i can use and get CHEAP. we all know what its like now A days and throwing 1-2K into a storage unit is just got my brain racking at the moment....im looking at work for things i can use and even checking houses along my commute to hopefully find something. im also going to put in our local sales on the net and make a WTB post. im just curious on what i should stay away from?
i did see a old gas unit probably for logging and holding diesel fuel? would that be bad? im thinking the hard part is making sure its good and clean.
and then we have metal BINS at work used to hold the metal chips the turn lathes and grinders cut. i could maybe take 2 of these and stack them on top of each other open sides against each other and weld it together AFTER the coils were in place??
im hoping the WTB ad will give me some results....i should stop at old barns and ask the owners what they have???

if you have any stories on how you obtained yours for cheap or FREE please share!?

Your local scrap yard might be helpful, especially with steel prices down.