I still get the occasional question about the cost of food and eating in Cambodia : but being asked whether one could get by on $3 a day was a new one. It is not an endeavour that I would be at all interested in personally pursuing.
My answer:
Yes, but it would be tough going and repetitive. For a tourist, it would be hardcore. Most Cambodians get by on a $1 a day but in practice, it is an extremely grim way to live; mostly involving cooking your own watery vegetable soup, a little fish paste and rice; and doing so for entire families rather than cooking alone.
It’d be much, much easier if you were cooking for yourself and buying produce from the local markets. While I was living in Phnom Penh, my weekly vegetable bill would come to less than $5 : but this wouldn’t include meat or rice; or the four or five meals out of the house a week. $21 a week would buy a good deal of rice and prahok.
To do it otherwise, you’d have to be eating at the very local joints especially market vendors at Orussei, Olympic Market or other outlying markets where you can generally pick up a decent bowl of noodles or something with rice for around a $1. You’d end up having to have one very light meal a day. My plan would be (if you’re eating outside the home):
Breakfast : Pork and rice; or a hefty bowl of khtieu for around 4000 riel. Coffee.
Lunch : Buy a baguette or two (a few hundred riel), whichever fruit is in season (another few hundred riel), and some pate or cheese to fill the bread. Interchange with ramen whenever you get bored.
Dinner : Pick up a preprepared curry/soup and rice from around Psar Kandal or Psar Chas. Alternate with a small fried fish occasionally.
My big tip (if you’re going to stay in one place/not move around too much) would be to buy a Rabbit-brand water filter (list of retailers(PDF)). You pour in tap water and out comes drinkable, bacteria and virus-free water. It’ll save you a hell of a lot on bottled water.