I suggested the following jackets, all petite sizing to help fit her tiny frame, and all under $100. My pick is this first version from Ashley B by Bernardo, which retails for $78. Click on any of the photos in this post to purchase.
A faux leather blazer is a cute option as well! This one is by Miss Sixty and retails for $78.
Two final options, both in black from Macy's, retail for $79.