You can go a long way with few resources:
If you want to put time into your SEO, an hour or two a week can go a long way.
It's not as hard as they say:
You don't have to know everything from day one. If you start by optimizing what you have and then expand slowly and steadily, you'll definitely get the most out of your work.
SEO is an investment:
If you buy ads, you lose the traffic from those ads the moment you turn them off. If you do SEO, the effect lasts well into the future.