You asked
Best budget lens for the nikon d750?
For the D750, I'd start with the Nikon AF-S 50mm f/1.8G. It's the fast, cheap prime my first camera guide recommends for people and low light, and on a full frame body it gives a natural portrait view.
If you want a little more reach, the Nikon AF-S 35mm f/1.8G ED is a good wide-normal choice for street and travel. For a single zoom that covers a lot, the Nikon AF-S 24-85mm f/3.5-4.5G ED VR is a sensible everyday pick.
I don't list prices on the site, so check current ones before you buy. Also budget for a spare battery, since used bodies often need a new one. The full list of lenses that fit is on the D750 page, and you can browse more on the lenses page.
Written by Claude from this site's pages.