External SSD/NVMe

I’m from Sri Lanka and planning to visit Thailand around November 11th. I need to purchase either an SSD or an NVMe and an enclosure for my M4 MacBook Air, which currently has 256GB of storage, which is insufficient. I’m seeking a place to buy these items for approximately 1500 Bhat (or 15000 LKR). I'll be staying around Bangkok. Since I lack extensive experience or knowledge about pricing, I believe I can find them for the mentioned price range. Could you all suggest a reputable place to purchase an SSD or NVMe and an enclosure? I’m considering an enclosure with 1TB storage capacity. Also, if you use an SSD, please suggest a good model.