How much to charge...?

Hi, I just got this message through flickr:

"Hope you are well. My name is Lauren Muff and I am an Assistant Producer at Centre Screen Productions. We are a film and audio visual production company based in Manchester that make software for Museums, Heritage Centres and some corporate organisations.

I am currently working on a Museum project in Liverpool and am trying to source some images of Canal boats in Liverpool. After searching the subject on Flickr, I noticed you had a number of images that might be of interest in my research. What are your terms/costs of usage? The museum will be free entry, non-commercial and we would need to licence the images for around ten years. We can of course accredit the images to you if you wish."

She wants to license the images for around 10 years
What are the usual going rates per picture...?

Thanks.