Another site you may want to check out is GraphicRiver. They are a microstock site that sells images at relatively inexpensive prices. They may not be as strict as some of the other stock photo agencies such as Getty Images would be, with regards to the quality of the images, the resolutions and such.
I actually purchase from Graphic River quite often since their whole pricing model is so much more simple and straightforward - no goofing around with purchasing "credits" which in turn need to be exchanged for images. There's also no need for costly monthly subscriptions that I don't need either, I can just simply buy one image at a time. They also don't charge an arm and a leg for video footage like many of the bigger stock video sites do.
Speaking of video, have you considering shooting that as well with your phone? If it shoots 1080p, that should be good enough to get you on to some stock sites. Video files sell for more too, and if you're good with programs such as Adobe Premiere or After Effects, you can style them up a bit further to look even more professional.