Flixbus is your answer to cheap intercity (and even International) travel. Go online, buy your cheap ticket in advance (the sooner, the cheaper) and away you go. The coaches are modern, have air-con, toilets, charger sockets and even wifi. Getting to/from Łódź is easy thanks to the city centre arrival/departure point being in the regional bus station, found inside Łódź Fabryczna Train Station.