I would go for one of the Samsung A series. Other than that, an OPPO.
I recently bought a Samsung for 6000 ish Baht. A little more than your budget, but it wasn't the cheapest model.
You might find a deal on Lazada, but to be honest, if I was buying a phone, I would prefer to do it in person in a shop.
Here is an example:
https://www.lazada.co.th/products/samsung-galaxy-a30s-ram464gb-3-i499300901-s888790189.html?freeshipping=1&search=1&spm=a2o4m.searchlist.list.i42.44f2bdbbVXIoMN