Here's a $300 adapter that would seem do the trick (although I haven't tried it myself):
VGA2USB | Frame grabbers | Products | Epiphan Systems
Also, depending upon what the nature of your tutorials are, you could take screen captures on the iPad, import them into iMovie, and do a voice-over as you zoom/pan to the applicable parts of the image. There are themes, transitions, music, to give a more professional feel. Use a program like ArtStudio to make your title slides and you can have a self-contained solution for under $10.