Ask HN: I am running AdWords to promote my iPhone App. How do I...

I am now running an AdWords campaign that links to www.gaiagps.com. Once they get to the site, I want to track how many people click the "Buy Now" button that brings up iTunes.

Normally, I could just put a tracker on the page I wanted to measure, but since I'm popping them off to iTunes, I need to track clicks on the link, not page landings.

My solution for now is this: I put a javascript Google Analytics trigger in the <a onclick> to track clicks of that link, and then I can cross-reference that against paid traffic.

However, does AdWords have a way to track these conversions directly? They have a "Conversion Tracking" system, but it seems to only work if they land on a page, not if they click a link, because you insert an Javascript snippet in the page to track conversions.

Am I missing something about AdWords Conversion Tracking, or is the GA the right tool to use here? I suppose I could also redirect them to a page with tracking code before I redirect them to iTunes, but this seems like kind of a hack.