Recommended accomodation:

University Hotel, al. Politechniki 3a
Newly remodeled university hotel. Across the street from the main venue and in the same building as the conference lunches.  
Single room 129.60 PLN + 15PLN breakfast
Double room 183.60 PLN + 15PLN breakfast
Reservations through email: recepcja[at]info.p.lodz.pl
or telephone: +48 42 631 2181  

Other accomodation within walking distance from the venue:
Hotel Qubus   (aproximately 230PLN for a single room, 315PLN double room)
Hotel Alicja - internet famous for its not very photogenic location, approximately 150 PLN for a single room, 170 PLN double room
Boutique Hostel (Stefanowskiego 17) - cheap hostel with shared bathrooms, 70 PLN for single room, 90PLN for double room, 12PLN breakfast

Map of the above locations.