There are numerous ways to travel across Thailand, some cheaper than others. The train is my favorite. It is cheap, much faster than a car, and fun. For no more than a few dollars, you can travel across hundreds of kilometers and arrive at your destination - Phuket, Chiang Mai, Bangkok, or whatever city you wish to explore. 

In Asia, grocery stores are hard to find and always overpriced. For this reason, locals rarely frequent them and instead run to open air markets. 

Open air markets are vibrant, fabulous places full of aromatic food, colorful clothing, fruits and vegetables, and anything else you can think of. The goods are cheap, and these markets can be found in every city across Thailand.