What is the least expensive way to get Thai currency, (i’m in Thailand, now )I have a Capital One visa and a bank debit card which happens to be a MasterCard if that makes any difference 
ATM, at a bank? 
TLDR : Answer Summary
To get Thai currency in the most economical way, expats in Thailand can consider several options: withdrawing from ATMs despite a 220 baht fee per transaction; exchanging money at banks without the ATM fee; using a local Thai friend for withdrawals; or transferring funds through services like Wise or Western Union. It's important to avoid ATM currency conversion fees by selecting 'no conversion,' ensure strategic withdrawal amounts, and consider bank options like Schwab that reimburse fees. Each method has its pros and cons depending on fees and limits, so it's recommended to assess the best approach based on individual circumstances.