Thais pay dowry to Thais all the time. Nothing unusual. In Isaan and Bangkok. In Isaan, the amounts are typically small 50,000 up to 200,000 baht (the higher-end if it's the woman's first marriage, educated and has no kids; and the husband has means). The foreigner paying 500,000 baht and up (I've heard some paying up to 1 million baht) for a divorced woman with kids are the fools. End of the day, it's all a negotiation and part of Thai culture.