I buy DTAC 15Mbps Unlimited sims from a Lazada seller called WPNMobile. Also included in the deal is unlimited free calls (Max 15 mins per call) within the DTAC network and 60 minutes free per month to all other networks. In 2021, the sim cost 1300 baht, in 2022 it cost 1210 baht (using coupons etc) and in 2023 it cost 1570 baht. Today the same sim costs 2590 baht. I don't stream videos on the phone and I use the sim mainly for getting money from ATMs, paying bills on the go, Line, some light browsing and emergency situations. So, this year (in a couple of weeks) I will buy a DTAC 15Mbps limited sim (60Gb/100Gb per month) as this will more than meet my needs and save me around 700-800 baht. They have other deals in their Lazada store
See https://s.lazada.co.th/s.oklXc