Did some, transfer costs beetween instances that serves as plot generators are f** expensive. You need TB of data transfers, for example 15TB to transfer on the internet is somewhere around 1500$.
This is mostly a problem for low-cost hosting that had some implied assumptions about how heavily used various components would be relative to the rest.
From what I understand, the network/algorithm is designed to prevent this from happening - either due to massively huge egress costs (I think you need to 'upload' the whole plot to the network after you have a verified proof), or for sheer data storage cases (some farmers/miners have tens of petabytes of plots already - i wonder how much that would cost to store monthly?)
You don't have to upload the plot after you have a verified proof. You do have to pay to store it, though, and that can be pretty expensive on AWS. If you just plot on AWS and store the plots elsewhere to save storage costs, you have to pay outbound charges on the plot files.