Help with gallery pricing...

Let me first thank everybody in advance for any advice!

OK, I'm a hobby photographer who has always worked for my own enjoyment and that of those around me. Photography is not my profession, but something that I love and helps to keep me sane.

I recenlty took some of my work into a gallery I know in NYC for framing. These were 20x30's shot with a combination of a 1Ds, 20D, and 10D, then printed by Ofoto. The gallery loved the work and offered to give me a section of the gallery for my photography. They are mostly interested in B&W versions of my cityscapes. This sounded like a nice way to supplement my income a bit without having to do much additional work. I don't want to sell him the files, so I'm going to have them printed and they can handle the framing.

The problem is, I have no idea how to negotiate pricing! If anybody can help me, I would be really appreciative.

Thanks!