Congratulations on having your work shown! When you sit down to discuss things with the store owner maybe you should point out how this would also be a help to him, because if you are going to have the prints matted and framed at that shop, than it would show off the work of the frame/matte place.... and maybe he will be gracious enough to make a deal with you concerning the pricing on having your prints matted and framed and such.
I had some prints displayed in a coffee shop and the owner and I agreed to a commision when the prints sold. As I remember it was 20% of the selling price....
*smile*