Here you can find direct bus connection. 400zł for return ticket, but it takes probably around 19h each way and I don't think anybody drives on 24th December - it's a holiday.
biletyautokarowe.pl
What are BiletyAutokarowe.pl? Coach tickets for nearly 300 000 connections. We offer you tickets to all routes from Poland to other European countries. Use of such low prices, as when purchasing tickets directly with the carrier. We do not charge for any commission. Compare all offers of every possible line and choose the cheapest and shortest route. You can choose from all the discounts and promotions. Save money and a lot of time! Buy a ticket even in 5 minutes. We give the opportunity to search the two largest hotel reservation systems with a single, simple-to-use search engine. Take advantage of the system and pay your order over the Internet, and tickets will be sent via e-mail immediately after the payment. Print them on any printer or collect it on the bus! You can also order tickets by phone and pay for it in the nearest traditional bank or Polish Post office.