Looks like you have already defined your ideal customer;
Next
You need to find out where the potential students spend their time - Online & Physically - and meet them there.
I'll start with the option, which I think has the most potential:
and the answer is NOT online - do not underestimate the value of networking; going to meetup's - interest clubs - sticking adverts on buildings, bus stops etc. with little rip-off pieces.
Online:
- do they spend time on facebook? probably the most undervalued forms of marketing
- quora
- you can do a very narrow targeting through Google Ads, but you did mention a very low budget.
Hope this helps
Sylvia

Hi, Sylvia here :)
Currently running my tech startup with secured pre-seed funding. My advice is simple:
1. Go to your your competitors social profiles
2. Set up your profile on the same platforms
3. Engage with their users
This is a guaranteed way to acquire new users (and followers)