Setting Fees

Really need this info asap. I've been asked to consult with a Medical Cost Containment Co. regarding expansion of an in-house bill review dept. I normally work in a salaried position. I have no real feel for what would be considered appropriate "freelance" fees. I'd hate to undersell my expertise. If someone could point me in the right direction for finding this info., I'd really appreciate it. Thanx mrj