PHOTOGRAPHY/CINEMATOGRAPHY: What lens/filter was used on these photos?

Hi! I'm about to get my first camera (A Nikon D3100) and I'm wondering What lens/filter/effect should i use to make my photography seem "indie/vintage" (like the following photos).
Also, what lens/filter was used to create each of the following photos (for example, a certain coloured filter like blue. Is it a gradient coloured filter?
:

Added (1). What colour filter do you think is used?

It is not a gradient coloured filter. If you don't like my answer then go and buy a gradient coloured filter.

Stop asking this.

That colour tinge is added in post processing, not by using a filter…

EDIT: You're not getting it… No filter was used for this effect… It was all done using an editing/retouching program

No color filter or gradient filter was used. I'd say there was some tweaking done in a photo editor, looks like saturation, contrast and color balance have been edited. As lovely as it would be to be able to just slap a filter on a camera to get these looks, it actually takes some time, software, and skill.