@craigslist you can get deals but u can end up with stolen laptop. So u have to be careful, you dont want to be dealing with police later. Now days, there are many tracking software, so they can come after you.
It depends on how computer savvy you are. If you are, then any brand will be fine, just go for the looks. If not, go with the bIgger and trusted brands: hp or dell. They have better after sales services and automatic updates. So you don't have to update and troubleshoot a lot later. They will be automatic. Anyway make sure you have continuous virus protection. Norton is really good and cheap if you buy 3/5 license ones with your friends.
Standard specs now days
I7 processor
8Gb RAM
1080p resolution
>750Gb HDD. If you can find hybrid HDD, it will really boost your performance (wish u can afford SSD, its really good)