In my mind, it's like leasing a car. Leasing is better for your cash flow, but buying is usually a lower total cost.
Outside of large volume S3, it's pretty trivial to beat AWS costs, assuming you have the human capability. S3 is a little different, as the capital investment required to host petabytes of data is very high, and Amazon's economy of scale is pretty compelling.
For most anything else, dedicated boxes at a colo or your own datacenter should be cheaper, assuming you have the people around to do it, etc
Outside of large volume S3, it's pretty trivial to beat AWS costs, assuming you have the human capability. S3 is a little different, as the capital investment required to host petabytes of data is very high, and Amazon's economy of scale is pretty compelling.
For most anything else, dedicated boxes at a colo or your own datacenter should be cheaper, assuming you have the people around to do it, etc