I see available dates in June with Continental to Warsaw for 60k round trip plus tax. If you and your friend signed up for the Chase Sapphire you would have 100k just from the sign up bonus. Since you can transfer points between accounts... one person could get the 50k bonus and have the other transfer 10k and purchase a round trip ticket. The other would be left with 40k which would be enough to purchase a one way ticket at 30k. So you would be left with paying for (1) one way ticket.