Thanks to the low cost of living and favorable foreign currency exchanges, visiting Thailand is very budget - friendly. You would not have any problems finding ATMs because widespread. They are also the most accessible when you need to get some baht. Credit cards are accepted in big establishments but most family-run inns and restaurants only accept cash. Have some available US dollars with you.
With just around 600 baht per day, it can already cover basic food, local transport and modest guest house accommodation. For 1,500 baht, you can live more comfortably in some Thai hotels and even enjoy some Bangkok nightlife.