It depends on the size of the cluster. If it's just a little blog and you just want it to be as cheap as possible, but still using K8s just for fun, it will cost you around $4/month on GCP (1 f1-micro node).
A minimal single host cluster runs fine for me on a $10/mo DO droplet with just 4GB RAM. It would probably work on the $5 droplet too if you weren't running much more than a blog.