Another alternative would be van boxes(from trucks). They're not as sturdy as shipping containers...but they can be gotten at truck salvage yards.here's an interesting link on an open air flea market/mall constructed entirely of the shipping containers...not too attractive, but quite utilitarian...
I enjoy the store/office building because it looks to me like child's play/ a stack of blocks..
Now here's an interesting solution for low cost/high density housing. I haven't looked at the specs on this either. Very cute and very high tech. I highly doubt that these are manufactured in an earth friendly fashion. This probably doesn't belong on this forum, but here goes: