The great thing about social media is your budget can be zero! And at times, zero budget is the most effective. This is because if you do everything on social media for free then all followers and engagement will be real. From my experiences it is best to start a Facebook or Instagram and start following, posting and engaging.
It will take some time but this is how you build a real following. Afterwards, you can look into paying for an ad to boost what you've got. However if you have no followers and run an ad, it might not be effective at all. A new follower will see your paid ad with the word "ad", go to your profile and see no followers and then not feel a personal connection at all.
Here you can find a new ebook we just released about free traffic! It will take more time but it will be worth it. Have you started an Instagram already?