laptop under 40-45k

hi there..
i am looking for:
ram: 4-8gb or more(the more the better)
graphics card:1/2gb(nvidia/amd whichever is best )
HDD:500gb/1TB
OS:doesn't matter
processor:i5(4th or 5th gen) or amd processor! if they are reliable and good as i hv no idea about that.

also i will prefer the laptops which i can upgrade later(RAM,Graphics)

if anyone can tell better laptops with higher config thn this plz reply..

also if there is some place where i can make custom laptops plz specify th place.
thankyou..