It's very inexpensive to travel in Northern Thailand.
At the time that I was traveling in Northern Thailand, the exchange rate was about 1 to 34 (USD to Thai baht), which is very, very good. Not only is the US dollar strong, everything is already less expensive there too. For example, I went out to a trendy, authentic Thai restaurant and got an appetizer, huge portion of an entree, a large Singha beer, sparkling water (which costs as much as the beer does!), and — with tip — paid less than $15 USD.
Food, alcohol, clothing, transportation, hotels, fun excursions — it's all inexpensive, even for quality purchases. I picked up some unique articles of clothing and indulged in food and drink that I would have hesitated to drop money on back in the States and still actually saved money while I was there since I wasn't spending what I normally would over the course of a week in California.