So you have to search and watch.
But the really bad news that gaming laptops do not age well so like the used car, it's best days are spent. With gaming laptops, many did not get proper care so I read folk getting used gaming laptops then exploding when the machines BSOD under load.
For gaming, you could do better with a PS3/4 or XBOX at the prices you noted.
Im trying to find a good 2nd hand gaming laptop on ebay for under £400. These are a must :
Intel core i3,i5,i7
At least 4gb ram, DDR
Nvidia graphics card , at least 550m , or any other fast AMD ones .
That's about it , I know 400 isn't alot but I'm looking for a second hand one on ebay or Amazon . An old laptop which is gone cheap now but still fast ? Any help appreciated , thanks .