All visitors, except citizens of Indonesia, Malaysia, Singapore, Philippines, Laos, Thailand, and Vietnam need a visa to enter Cambodia. The official price for a tourist visa is 35 USD and is valid for one stay of up to 30 days. It is no problem to buy one at the border. My hostel was 3.50 euro per night.
Siem Reap: Angkor Wat (ancient temple complex). Entry is around 18 euro.
Amok is one of their traditional food. A coconut milk curried dish less spicy than those in Thailand. I loved it. A meal is less than 3 euro.