Your friend sounds as if she’s having some issues. Is she married? Alone? Doesn’t like your fiancé? There’s more to this than the monetary value of the gifts.
I agree. I can't imagine anyone, especially the Maid of Honor and your best friend, saying anything like this! I love your gift idea.

When Scott and I got married last year, our "bridesmaids" were our daughters. We bought each of them a nice silver necklace with a cross on it, to wear, but they truly weren't that expensive. It's not the cost, it's the thought, and obviously something else is bothering your friend. I'm sorry she has upset you at such a busy and important time in your life.