I don't think this directly answers your question – but exchanging money at an airport, whilst may be convenient – is not the best option. But if it's only $100-200 the forex loss may be non-trivial, there are ATMs and money changer booths in the arrivals hall, most of these are operated by the banks in Thailand (SCB, K-Exchange, KTB, etc.). There's also one behind Border Control, iirc.