Motorbikes, cars and 4WDs are available for hire from most guesthouses in town. Motorbikes are usually US$5 to US$8 a day. Cars are available from US$30 a day and 4WDs from about US$50 a day, but prices rise rapidly the further you want to travel.
Cheang Torn Moto (012 960533) has some 250cc dirt bikes available for US$10 per day, but maintenance is an issue. Norden House has reliable ones, but at US$25 a day. Local guides with motorbikes offer their services around the province and rates range from US$8 to US$15 depending on their experience, level of English and where you want to go.
For something cheaper and more environmentally friendly, consider a bicycle (US$1 per day), available from some hotels and the bike shop on the main drag.