[Sangetsu]

You are stuck with the old tickets, like it or not. I don't know if they are transferable or not, if so you might be able to sell them to someone else.

For cheap tickets, you can try bidding on a ticket at Priceline.com You select your travel dates, and look at the options available, at the bottom of the page is an option to bid on tickets, I've often won with a bid that is half the normal price. You might as well bid on round-trip tickets, for whatever reason, they are almost always cheaper than a one-way ticket.

Always use a travel/airline credit card (if you can get one) to buy tickets, one of their usual perks is cancellation insurance on airline tickets.