Is there a way to put decks you've made into your inventory quick and easily? I did this backwards and made the decks before making my inventory.

Also, is there a way to display the pricing for a foil version of a card?

The best way to put a deck into your inventory is on the deck page go to View > Print (In the upper right corner). Copy/paste this list into the the Inventory Import List.

And no, there is currently no foil pricing because the TCGPlayer API does not return that data at the moment.