This is a cute little oral mech exam kit. I know I'm always buying a new pen light!
http://www.asha.org/eweb/OLSDynamicPage.aspx?Webcode=olsdetails&title=NSSLHA+Oral+Mech+Kit
Another idea would be to buy her a big tote bag that she can use for therapy materials. If she's working with kids, you could fill it with some kid stuff. Bubbles, play dough, Mr. Potato Head, markers, noisemakers, puzzles, and kids books are things I use all the time with my clients.
Very thoughtful of you!