The Sony A7 was and still is the cheapest way to get full frame video. Lenses included.
Its cheap at under $1000 used. Or slightly above at Amazon:
Sony a7 Full-Frame Mirrorless Digital Camera – Body Only
But its also cheap in that its mirrorless. You can buy very nice old glass for very little money and use adapters.
And like most will tell you, glass i the real expense.