Chapter 2.7 : How do the various options of Storage Gateway: File Gateway, Storage Mode, Cached Mode and VTL compare in terms of speed and costs ?
Like most AWS services you can go to the pricing page for cost details for each service: https://aws.amazon.com/storagegateway/pricing/?nc=sn&loc=3. As for performance it depends on what you are doing and the speed of the connection between the client sending/receiving the data and the AWS services being used. Since all are caches of remote data in the on-prem network performance can also be affected by what is in the local cache and what needs to be retrieved upon a request. To me the best part of the gateway products is that the on-prem clients and apps get local performance to write new data. The data is then sent to AWS on the backend.