Let KAYAK do the searching
Based on KAYAK hotel searches, the most popular destination is Queenstown (51% of total searches to South Island). The next most popular destinations are Christchurch (26%) and Wanaka (12%). Searches for hotels in Te Anau (11%) are also popular.
KAYAK users have found double rooms in South Island for as cheap as C$ 62 (Fox Glacier) in the last 3 days. The average price is C$ 220.