Ask them to make you an offer first, then use that as your absolute bottom plus expenses and such.
I used to do then when i was in school. Make sure to write a simple contract granting them the use of your images for this or that purpose. Later on, you might want to sell the same images to someone else. But don't come dragging a ten page release form - I saw a pro do this once, and the company were so offended they bought my images in stead right there and then
