I have familiarities with software automated build tools ( such as Automated Build Studio). Now I am looking at ETL tools.
The one thing crosses my mind is that, I can do anything I can do in ETL tools by using a software build tool. ETL tools are tailored for data loading and manipulation for which a lot of scripts are needed in order to do the job. Software build tool, on the other hand, is versatile enough to do any jobs, including writing scripts to extract, transform and load any data from any format into any format.
Am I right?
It is correct that you can roll-out your own ETL scripts written using a development tool of your preference. Having said that, ETL jobs are frequently large (for a lack of better word) and demand considerable administration and attention to minute details (like programming). ETL tools allow developer to focus on ETL tasks -- as opposed to writing and debugging code, although that's part of it too. There are some open-source tools out there, so you can get a feeling of what an average tool does, before jumping into custom development. For example, more expensive tools provide data lineage, meaning you can (graphically) track every field on a report back to the originating table through all transformations (versions included); after a corporate merger that's quite a task to do.
For example Pentaho has community edition; if you have MS SQL Server, you can get SSIS. Also see if you can find something here.