Teaching English in Asia is a great way to experience living in another country and pay back your student loans at the same time. One of the best options financially is to teach English in Korea as most TEFL jobs there include for round-trip airfare, furnished housing, 2.2 million won($2,200)/month starting salary, one month severance pay after finishing your contract, 50% of pension plan, and settlement allowance. Combined with Korea's relatively low cost of living, savings potential is high and you can expect to have $1,000+ left over each month even if you go out for food and drinks. Also keep in mind that your last paycheck will be 3 months' salary — one month severance pay, pension reimbursement, and last month's salary!
Teaching English in Japan is also a popular option, and athough the savings potential is not as high as Korea, it is still possible to save a fair amount of money. Going out for drinks and food can be expensive in Japan, and these will be your biggest expenses. TEFL/ESL jobs in Japan start at salaries of around 250,000 yen, or $2,250 per month.
Taiwan is another good place to teach English abroad if you want to save money. At $1,500 per month, teaching English in Taiwan doesn't pay as high as Japan or Korea, but the cost of living is low enough to have $500-700 left over at the end of the month depending on what you do.
China is the the economic miracle of the 21th century and it is becoming more and more popular as a place to teach English. Salaries in Guangzhou, Shenzhen, Shanghai, Beijing, and other economic centers have increased significatnly in the past 5 years, and you can expect to make around $900-1000/month, more if you have certification and experience. The number of people with disposable income in these areas increases every year and many are eager to learn English with a foreign teacher. TEFL jobs in China include a free apartment and the cost of living is very low!