This is a great thread and a very compelling read. Such an important question! Thank you for putting it out there.
I have learned to say thank you and refrain (the operative word here) from degrading myself, or excusing myself, or veer towards how or where I got it or how it was on sale etc. because all these statements, I came to realize, make ME feel better maybe, but do nothing for the person who complimented me. If I bring myself down, it's almost even not nice to the person because it's as saying that what (s)he complimented about was not worth it.
I like MsMary's approach because each little addition she offered are not negative, they are full of humor and also present the interlocutor with a possible fresh conversation topic (such as - Oh, where on vacation did you go?).
I am trying out this idea: I try to turn it towards the complimenter and focus on them, and then say something nice about the fact that they noticed ("Oh, how clever of you to have noticed that..." or "How kind to take the time to complment me like this").