Diamond Lakes is pretty nice and you should be able to get a 1 bedroom for that price. There are several just off of Congress such as Bayou shadows, Cantebury square, and Summer Place that are all affordable and pretty safe. They are not high end apartments but i lived in all of them while in Lafayette and never had any problems. They just dont like alot of loud music and partying which is why i had to move out of all of them
This was 6 years ago so things may have changed.