As other posters have mentioned, the incument companies rebranding to Observability definitely are expensive, because they are charging in the same way as they do for logs and/or metrics: per entry and per unique dimension (metrics especially).

Honeycomb at least charges per event, which in this case means per span - however they don't charge per span attribute, and each span can be pretty large (100kb / 2000 attributes).

I run all my personal services in their free tier, which has plenty of capacity, and that's before I do any sampling.