Look for an online stock price calculator, there's a few around. You can try:
Stock Photo Price Calculator for starters. Theres several others, some are free, some you have to register to use, and there's some programs you can pay for. These will all give you VERY loose numbers, but remember the business will be using her images to make them money, so don't give them away.
Generally for pricing stuff like this (photos used for commercial or advertsing, not strictly editorial) the price depends on how many units are being printed, how large the image is and other things.
Remeber only to give (license) reproduction rights, NEVER sign over full copyright to the photos without a great increase in compensation.
Just my 2 cents, good luck!