Hard to find a cheap 2nd hand 15 inch in Thailand, why buy an old laptop compared to a new one.
These days the parts are all soldered in. so you cant replace parts.(global warming)?
After searching แหล่งซื้อ-ขายของออนไลน์ - Kaidee
I found a 2012 dell precision m4600 for sale. and built it up a little. with better hdd's.
replaceable 1080p ips screen
replaceable i7270qm cpu
replaceable 2x4gig 1600mhz ram with 2 spare ram slots
replaceable separate replaceable gpu
replaceable 256gb msata drive
replaceable 2tb hdd
replaceable dvd/blueray drive
replaceable bluetooth card
replaceable wifi card
replaceable mobile card
replaceable camera/mic
2xusb3 ports
2xusb2 ports
seperate mic/spk
sd card slot
hdmi out
express card slot
and more
cost 15,000 baht all up.