Rooms in SihanoukVille start at FREE per day. A few places on the beach offer free rooms to backpackers. But don't expect a lot. After free, comes $2/day for a bunk bed in a dorm room. The next step up is $7 per day - which can be found at over 70 guesthouses here. Most of these include a double bed, bathroom, TV and sometimes fridge. (you don't get air-conditioning or hot water). Some of these can be quite nice. Most of these rooms are found downtown, on Victory Hill, or on Beach Road near Serendipity Beach. $13 and up gets you the TV and hot water at many places (but it's a bit more right on or near the beach).
Angkor Wat model at the as yet to be named Hotel. You can't stay here
Most places will give you a discount for prepaying for a week or month at a time. Usually, a $7 room can be rented for about $90 to $150 a month. Prices are generally higher in the Winter (beginning the start of November through the end of February) and lowest in the Summer (June to September). The Summertime is when it rains about half the days or more. Please note: on a few holidays, every room in SihanoukVille is booked and prices can triple for several days. This is usually around Christmas/New Years (end of December), the Chinese/Vietnamese New Year (early / mid February), and Khmer New Year (Cambodian) in mid April.
Best bet, pick a general destination before you get to town. Downtown is the easiest, with the most services and in the center of all the beaches. You can walk from the bus stations to many budget guesthouses. Several places have rooms with bathroom, cable TV, and fan for $6 and up. Only problem..... no beaches.
Victory Hill is on or close to Victory Beach. Nice view of the islands and port in the distance, tree lined beach, and the most backpacker guesthouses, services, and restaurants in one area in town. About a 5 minute ride from downtown. About $1 or less for a motorcycle taxi. Rooms start at $4 here. The walk from the top of Victory Hill to the beach is about 3 minutes.
Green Gecko on Victory Hill
Ocheteaul / Serendipity Beach. Most popular destination in town, and most expensive. Off the beach you can find good, cheap places to stay and eat. Many new services opening up by the day here.
If you're just arriving, and planning on going to anywhere, you'll be "met" by motorcycle, tuk tuk, and taxi drivers. You might want to get a quick ride into town, about 5 minutes from the bus station, or Victory Hill, about 2 minutes. Sit down and get a drink or meal, look over a map, question the staff there (you can find English, French, Irish, Swedish, German, Japanese and a few other languages here), and take a motorcycyle taxi or Tuk Tuk to your destination. If you're going to Victory Hill, you can just have them drop you off and walk around looking for a place to stay. To Ocheteaul / Serendipity, you can get a ride to the Beach Road, and stop in Monkey Republic or Utopia (which will probably both be filled up anyway) and ask their advice. There are several backpacker places nearby and everyone will be glad to help you. Utopia, Sakal Guesthouse, The Big Easy, all have dorm rooms here as well.