What about an Olympus em5 ii with ef mount sigma f1.8 18-35mm & metabones speedbooster? That's 2,600, 2,750 with variable nd by tiffen. Actually it might be less cause that's for the xl metabones. You don't get 4k but you invested in a good ef lens for future camera bodies and a good run and gun stabilized body. Stabilization in post is a headache I'm finding especially for gh4 4k unless you have a really new and high end machine/software which will cost even more to invest in and still add time. Your light and stabilization needs with this setup would be mostly taken care of. With the gh4 your limited to tripod work, investing in more lighting and a3 axis stabilizer, which only some will support the heavier glass a metabones uses and again will put you way over budget. You're better off sticking to 1080p right now and if that's the case the em5ii will save you a lot of time at the sacrifice of some quality, I think it's mainly moire and aliasing that it's not great at from reading. If so you could get it and sell the body in a year and only be out a fifth of your total investment.