Hello Evee,
You have described your teeth as "crooked". I take that to mean that you see your teeth as being in the wrong positions i.e. not aligned or "straight".
Crooked teeth can be moved to the right position i.e. "straightened". Moving teeth will require braces or clear aligners.
You have asked for the cost-effective method. Metal braces cost less than ceramic braces or clear aligners.
I would not recommend veneers or crowns as they do not correct the position of your teeth but merely mask their positions. Furthermore, veneers and crowns are more invasive in that they require cutting of the teeth.