then get from someone like aasim.
the only other seller i have bought from online is oldlappy - still wouldn't vouch for them as it was a long time ago and dont know them otherwise.
Even if you buy from a reputed seller - given you are new to this, you will need servicing at some point, and you can't do that online - so you need to take a leap of faith with someone local.
even I have been screwed buying online from a reputed seller - I bought an elitebook 840 g1 for 15k online, thought it was a deal, found out it had no webcam, Bluetooth didnt work, and monitor was a crappy TN panel which the 840 wasnt even supposed to have in stock form. I contacted the seller, and fair enough, their listing never mentioned Webcam or BT, and specified only 1366x768, and it did match the description.
If you are new to this and do not know how to inspect a used laptop, I would suggest you find someone who does or even better - you learn.