AS I SAID ABOVE "buy it to the cheapest foreign destination" , in other words, an onward ticket, put it on your credit card and later cancel, it costs NOTHING and is cheaper then a rent a ticket. I dont find it fun but I do find cancelling a ticket online is easy, costs nothing, keeps your options open and immigration happy.
It is only "expensive" in the fact that you need to have the funds to buy an expensive, but refundable ticket,