Are you sure about the 300'? That is a long way! For that kind of distance, you may be better off looking into a point to point wireless bridge as I highly doubt that any wireless camera alone would have the range and sensitivity to support a connection that far. Ubiquiti makes bridges and would be a good fit. FOr about $130.00 plus any pole mounts you need, this will give you connection between the 2 locations.
https://www.amazon.com/Ubiquiti-Nanostation-Outdoor-5GHz-locoM5/dp/B00HG1CTDW/ref=pd_lpo_147_tr_t_2?ie=UTF8&psc=1&refRID=C3DC068TPPQ19JYYMWWM
You could then purchase any wired camera that would be suitable for your location.
