Panasonic GH series tend to be the go-to for serious video shooting, at least in the m43 world that I'm familiar with.
GH5 has been announced but not shipped yet so the GH4 could be on heavy discounts, possibly entering the required budget range.

Blackmagic is another interchangeable lens cameras that are used in serious videography and from the reports I've read about them, are very good bang for your buck for what you get. And what you get is RAW video. I believe they have some entry level cameras in the sub $1000 category.