Looking for a cheaper option for a anamorphic lens? well the moondog labs lens might just fit your needs. For $175 it can give that 21:9 ratio on a budget. This lens is not a gimmick but does have a few kinks but is well worth the purchase. This lens will give you that cinema level look right from your pocket.
Here is some test footage shot on an iphone 6s+ in true 21:9 aspect ratio enjoy!
Moon Dog Labs Website : https://www.moondoglabs.com/store
iPhone hand Grip : https://www.thingiverse.com/thing:2653846