My suggestion would be to focus on some quality, organic SEO. Since your budget is limited, you can apply search engine optimization yourself and for limited funds. You just need to learn the ins and outs of SEO and apply it to your website and products one by one.

I recently recorded a podcast on the subject and if you are interested, you can find it here:
https://www.web-savvy-marketing.com/2016/05/ecommerce-and-seo/