Oops..I wrote down the wrong print size

It's actually a 16 x 12" print, roughly A3, I quoted the size of the frame it was in
Thanks for the advice all, I was also wondering about asking her if I could borrow some exhibition space, maybe even on a trial basis...she owns the
Gallery jointly so it wouldn't only be up to her.
Around £25 to £30 sounds about right for a "mates rates" basis, will suggest that and see if she thinks it's fair

I'd still get a decent profit as well as covering the printing costs. I use photobox so would ave to factor in the greater delivery and print costs for a one off.
thanks again!!