A call to our plumber this morning confirmed a minimum service call charge of $150, too much to justify an earring rescue.  However, my next question to Chris was about what it would cost for him to replace the old metal pipes (which he did mention could possibly "disintegrate" when being removed during said rescue) with plastic, and he said it would "likely only be $20 more." Since I recently received a $25 rebate in the mail from them I hope to end up with just the minimum charge when all is said and done.  

We are scheduled for the work on Monday, when I should finally be able to use my sink again (I have really missed it!) and may even get my MIA earring back.