Let KAYAK do the searching
Based on KAYAK hotel searches, the most popular destination is La Fortuna (71% of total searches to Arenal Volcano National Park). The next most popular destinations are Tilarán (14%) and Monteverde (7%). Searches for hotels in Chachagua (7%) are also popular.
KAYAK users have found double rooms in Arenal Volcano National Park for as cheap as $31 (La Fortuna) in the last 3 days. The average price is $125.