You're not looking at the same price for paining versus replacing the balusters. Here are 2 ideas for painting which would make a huge difference.

The stairs in the picture look good. But My wall color is gray and floor color is honey oak and can’t afford to replace them now. So thought of changing the balusters.

The ones you already have look good with your flooring. I would just leave well enough alone. They look to be in great shape.