* 8Gb ram is good
A couple of pointers for shopping on Ebay:
* you may choose to buy extended warranty from squaretrade.com, $30-90 for 2 years, it used to be an excellent deal because everything breaks in 2 years
So your search for “dell latitude e7450”, only “buy it now”, sorted by price+shipping descending, make sure that return policy allows you 30 days, and look into description of blemishes, and decide from these.
Ebay is an excellent place for hardware refurbishers. There are facilities that will process tens/hundreds of used laptops and list them for sale. They deal in volume, you get a good deal and the vendor accepts returns by USPS no questions asked.