Since the movie is so new, you are going to be hard-pressed finding one pre-styled and I have never seen a wig similar to it online before(sorry!) so I think you're going to have to try styling it yourself. This wig would probably suit your needs quite well- http://www.epiccosplay.com/40-natura...splay-wig.html
The nice thing about Epic Cosplay wigs is that they are very silky and don't tangle easily. That does mean it's a little more difficult to style it with product, but not impossible by any means.
You can also take a look at Arda wigs, but I browsed and couldn't find one that could work very well. The nice thing about Arda wigs is that they style very well and are easy to work with in that respect. The downside is they tangle worse than some of my eBay wigs! So basically the polar opposite of Epic Cosplay. If you don't mind straightening one of their curly wigs you might be able to use it!
Another site you CAN look on is Five Wits, but I warn you that sometimes their long wigs don't look as good in person(most of them are okay but there are a few that I was horrified by!) so you might want to look up reviews for a specific wig via google before buying it. They also style extremely well but tangle.
Finally, it looks like that specific style is going to be extraordinarilly difficult without a lace front wig so you can pull the hair away from your forehead without fear of revealing the cap. Unfortunately, those are also extremely expensive, definitely over $50. So you might have to either carefully modify the cap so it won't show or simply sacrifice some accuracy for the sake of looking good. I'm sure you can find tutorials if you google it though.