I don’t know of any, hopefully someone else will respond.  However, when I am looking I often check ASHA’s “find a professional” and then I ask that person or practice where do they send clients for AAC evaluations.  I also contact the reps area such as a Tobii-DynaVox rep (because the website allows you do a quick zip code search for reps) and ask for an SLP contact number and often they can recommend a few.  This way I know I am getting someone who normally does device submissions.