If you will be doing follow cams in the park. For that price i would pick up a 14mm samyang or something of the sorts. If it will be on a tripod, then pick up a 50mm f1.8 for around 100 bucks. If your price point was higher then I would definately look into a tokina 11-16. I have one, as well as the 50mm and I love them both!
For a battery grip, i picked one up on amazon for around 30 bucks. It came with a few off-brand batteries which I havent had a problem with so far. The brand was called Meike