Ranking site

I have an Amazon affiliate site that's over 1 year old and I'm wondering if I should keep working on it or just cut my losses. I put a lot of work into it initially including some basic linkbulding but pretty much gave up on the site after about 6 months when I wasn't seeing any results. Even now the keywords the site is targeting have low competition and good search volume but it is receiving almost no traffic. According to SEMRush the site is ranking for 123 keywords with the highest ranked page sitting at 20 in the SERPs.
I was thinking about buying some PBN links but I'm on a tight budget and can't decide if it's worth it or not.