Poznan's accommodation rates are reasonable -- except when a trade fair comes to town and hotels unabashedly jack up their prices by 30% to 40%. The summer months are fairly safe, but the rest of the year sees a trade fair at least once a month (check www.mtp.pl for the trade fair schedule). Since business travelers fill the hotels, come on weekends -- when many places offer reduced rates.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.