Yes, there's basically two tiers of Workers for self-service: Free, and $5/month. You only get access to KV on the $5/month plan currently. You do get better speed and more CPU time for those workers, but it's strictly speaking KV that requires the $5 here.

> But conceivably, you could host your blog on the free tier, right, by compiling the static content into the hosted app?

Yes, you could! There's a size limit to a worker though, so for a large site you may not be able to.