I have a fearful foster dog right now and yes, she is considered a high bite risk because she is fearful. She would never lunge at someone just because they walk near her, or try to pet her. But because she IS fearful I don't feel comfortable walking her down busy public streets where any ol' Joe can run up to her and pet her, just in case. We go hiking down wooded paths where we meet very few people, so it's not as stressful for her. I also take her to friend's houses for socialization, and to some of my classes since the people in there are dog savvy (it's an animal based program).
She has come a long way in the short amount of time I have had her, and I owe it all to the guidance of a fabulous trainer. Even though it may be expensive, I suggest going all the way and getting the best trainer possible. The way I looked at it when I signed up for classes was this: I'll drink Pabst instead of Bass, I won't eat out as much, and I won't do any frivilous spending. I wanted only the best for this girl, even though she isn't my dog, and was prepared to make small sacrifices to get there. Since she is your dog I don't see any issue in making those sacrifices, or at least dipping into the doggy emergency fund because a fearful dog in need of training is an emergency.
"All changes, even the most longed for, have their melancholy; for what we leave behind us is a part of ourselves; we must die to one life before we can enter another." -Anatole France