I'm looking for a good alternative to Camtasia Studio - really just the video editing part. My current workflow looks like this:

1. Record audio (with Audacity)
2. Save screenshots of the subject matter (websites)
3. Import audio and screenshots into Camtasia
4. Use the zoom and callout tools in Camtasia to go along with the spoken audio and highlight certain parts of the sites

Given that Camtasia costs $300 (I've been using a trial version), I'd like to find something else that can do this well. I suspect that a lot of the pricetag for Camtasia is because of the screencasting features. I've tried Sony Vegas Movie Studio, but it was really a lot more than I need. I'd like something relatively simple (so that new users can pick it up relatively quickly), with the zoom and callout functionality that Camtasia has. Any suggestions?

Edit for clarity: I'm looking for a program that will let me combine the screenshots and audio, and (most importantly) that has features equal to or better than Camtasia for text overlays, highlighting areas on the screen, etc.