You're going to need to search out and find the parts. They are mostly older and not new anywhere anymore. You'll be looking for people selling used/old STS towers and Y clips. As for the crossbars and wind fairing, Amazon actually beats eBay for some things.
Do a search for "Yakima STS" and you should find some towers. Try to find a set that comes with clips. I used the Y30 clips, but they needed to be modified - I don't know if there are better/other options or any clips that would work without modification.
Watch the Q-tower installation video on youtube, it's helpful. Even though the STS towers are not exactly the same, it helps with the general concept.
‪How to Install a Yakima Roof Rack‬‏ - YouTube