Yes it's enough to buy a respectable hybrid; you won't get the best ones at that price brand-new but it's worth looking around for secondhand bikes.
$400 will buy you an average quality new hybrid or a very good quality pre-owned one. Brand and model is very much a question of personal taste; I like Specialized brand bikes but at the moment I'm quite happy riding a 20 year old Ridgeback MTB because it suits me.