I went and made several bids of increasing value on a single item (8000, 9000, and 10000) before noticing that instead of taking the difference out of my gold balance (8000 the first time and 1000 each time after) it took the whole sum of the bid from my account. I have since been outbid, and have no desire to continue bidding. Will I receive my gold back once the auction is complete?
You do get the gold back. When a bid fails (usually due to the item being purchased by another player) or you are outbid, the gold goes to the Completed tab.
Sometimes the gold will not appear there right away. If you successfully complete another purchase or close/reopen the Auction House, all your failed bids should be updated.