When Donald Blake awakened Thor from the "Void of Non-Existence", the Asgard was already destroyed by the Loki's Army. From where did Thor get the money required to purchase resources to rebuild Asgard on Earth? As Blake, Thor was merely a Doctor who can't have that amount of money to build an entire city.
He didn't rebuild the city with conventional supplies. Instead he used magic to call the city forth. In general, normal stone and lumber don't float above the ground. While they glance over it in the first few issues of Thor, in Iron Man you see him process a bunch of reports about the "city just appearing".
Since Thor can call forth stone and wood, there is no reason to suppose that he couldn't call forth a bag or ten of gold when he chooses.