We partner with and use PBF (Powered by Fivetran) for some connectors, which we believe are best in class. In addition, we are using Singer Taps and have also custom built some connectors. There are no additional fees for extract-transform-load, whether Fivetran or any other ETL service (we cover those). The primary additional data costs are for a BI tool, though there are a number of free options to connect to.