Should I buy new d610 or used d800 in 2018?

I’m a 22 y/o “amateur” photographer from Serbia seeking for help.

I used d7000 for some time and I want to upgrade it. I used to shot b-days and events with it, a little bit of weddings, and thinking about moving to ff. 

Nowadays, because of the faculty, I don’t shoot weddings anymore, I’m more interested in street/portrait/studio/candid/everyday life photography. So please tell me what would be your chose here. Just to know, here in Serbia, the price is the same.
New d610 is 1100 euro vs used d800 is around 1000 with 30k shutter. I don’t care about the weight of the bodies. 

Also, I own only 1 lense, 18-140mm. Other lenses I used are from the colleague I shot with. What I like now are the prime lenses. I have an eye on 35mm and 85mm, what do you think it should be my first prime to get, maybe nifty fifty 1.4G?

Thanks on the comments and I hope so this post will help the others

Hello guys, I’m new to this site, and I already love it.I’m a 22 y/o “amateur” photographer from Serbia seeking for help.I used d7000 for some time and I want to upgrade it. I used to shot b-days and events with it, a little bit of weddings, and thinking about moving to ff.Nowadays, because of the faculty, I don’t shoot weddings anymore, I’m more interested in street/portrait/studio/candid/everyday life photography. So please tell me what would be your chose here. Just to know, here in Serbia, the price is the same.New d610 is 1100 euro vs used d800 is around 1000 with 30k shutter. I don’t care about the weight of the bodies.Also, I own only 1 lense, 18-140mm. Other lenses I used are from the colleague I shot with. What I like now are the prime lenses. I have an eye on 35mm and 85mm, what do you think it should be my first prime to get, maybe nifty fifty 1.4G?Thanks on the comments and I hope so this post will help the others