Rates in Antwerp are generally lower than in Brussels. You find the widest range of accommodations around Centraal Station and fewer choices within the town center. However, many of the big hotels are on the city's outskirts; most of these are geared to business travelers and offer substantial discounts for weekend stays.
The tourist office has a free, same-day reservation service -- you make a small deposit, which is then deducted from your hotel bill. They also publish a booklet listing all Antwerp accommodations and rates.
A word of warning to budget travelers: The phrase "tourist room" that in other cities means an accommodations bargain in a private home means something rather different in Antwerp -- it's a discreet way of advertising very personal services that have nothing to do with a room for the night.
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.