The Thai government seems to want to make it impossible for the traveler to stay and work in Thailand. New visa restrictions limit tourists to 15 days in-country before having to leave if they arrive over a land border, and 30 days from an international flight. This means that the time honored tradition of vagabonds working under the table as English teachers has become almost impossible. Fortunately, there are ways around this, but not without some risk.
One way to manage to stay in Thailand for an extended visit is to secure a volunteer or student visa. This will require taking classes and collecting the proper documents, but is certainly possible. Another more exotic (and dangerous) way of doing it is to enter Cambodia on a business visa, get a six month or one year extension there, then get smuggled back across the border on a speed boat from Koh Kong. Hopefully you don’t get caught… Once the Cambodian visa is due to expire, it will be necessary to smuggle yourself back across the border to Cambodia and exit from there. This is difficult, but it is certainly done.
English teaching rarely pays more than US$10 an hour, and usually less. Jobs are there, but Bangkok is increasingly a sketchy place to do it, as the police sometimes stage crackdowns on schools that hire illegals. Smaller cities are safer, but wages are lower and jobs can be more difficult to find.
There are other options, such as working as a tout, smuggling and selling drugs, legal international trade, or of course bar and restaurant work. Arguably, smuggling drugs would be the most profitable, with huge markups from Laos or Cambodia to Thailand, but Thai prison is not a nice place to spend 20 years of your life if (when) you get caught…
Fortunately, Thailand is still quite cheap, and an excellent value for the money. In the high season (December to February), prices on guesthouses soar, but even in Bangkok it is always possible to get a decent place for under US$10. The average price for a guesthouse during high season throughout the country ranges between B150-B200 ($4-$6) for single room with shared and sometimes private bath. Air-conditioning is usually available for B350 or less. The fewer tourists in the area, the cheaper it is, therefore small towns are cheaper than cities and major tourist destinations.
Food is very cheap, with delicious meals available at the market for under US$1. The servings are small, but a budget of $5 a day for food would allow the travel to exist without going hungry at all. Meals are often accompanied by free water, though the glasses aren’t washed…
The price of clothes and other consumer goods are a fraction of what they would be in the West, and some people make money trading things they buy in Thai markets back home. It’s a difficult business that requires connections and a keen business sense, though.
Transport costs are very low, with trains running halfway across the country for under $US15. Buying tickets from travel agencies will be more costly, but may save you money on taxis, which can be expensive.
Overall, a budget traveler should make it fine with US$20 a day. US$25-$30 a day will allow for more comfort and nights out. Beer can be a little expensive- a large bottle of Singha at a supermarket is B45. At a bar it is more like B65-B75. Illegal drugs are very expensive, though prescription drugs are widely available…
Living in Thailand and getting an apartment with a kitchen will allow a foreigner to easily live under $500 a month, a bit more in Bangkok.