Why in world would anyone consider this any kind of real option...?
I bought a used T440p on ebay, replaced the screen with IPS, upgraded to 16gb, upgraded the cpu to a legit quad corei7, new battery, replaced the primary drive with a 256gb SSD and exchanged the CD bay for an additional SSD for storage... total.. $530.. I have a Latitude E6430 I've done most of the same to except the screen and it was less than $400... so why would anyone consider this a good deal when you can get a lot more for significantly less money???
Even if you can't personally do these things, there are plenty of videos showing you how, and if you don't have the confidence to do it yourself, it's not hard to find someone or even a shop.. I can't help but wonder if the author is an Apple person.. wouldn't be surprised considering they haven't been upgradeable since like the 2012 NON-retina display...I think?