This article has been moved here:
http://dennisplucinik.wordpress.com/2007/07/31/google-adwords-technique-1000-revenue-increase/
This article has been moved here:
http://dennisplucinik.wordpress.com/2007/07/31/google-adwords-technique-1000-revenue-increase/
I recently blogged about how the change in even a single word in an ad can have absolutely huge impacts on both CTR and conversion.
http://diorex.wordpress.com/2007/01/26/changing-one-word-in-an-ad/
I would also point you to my post on how to determine how many clicks are enough,
http://diorex.wordpress.com/2007/01/29/margin-of-error-in-testing/
Otherwise I think you are doing much more than many of your competitors, which can only serve you well in the long run.
I put myself through college on baseball cards (and owe my love for stats and spreadsheets to them), great to see that some interest is being revived in these collectibles.