I've bought displays from Craigslist and from GAF BST.
While partially true, something like the VG248QE has a 3 year warranty based on serial number, so ASUS would fix it if something went wrong.I'd recommend buying new. Craigslist can be great and I've never gotten burned and found some great deals but you just never know and I still accept the fact that anything I buy could work for a week and die and there's nothing I can do.