UPDATE: Well now the Swan is quoting me $150 for the cake I requested -- a 10" chocolate cake with strawberry filling, decorated in a "princessy" theme, but no characters, no topper.
They really are not set up to do custom cakes -- they offer four basic flavors (chocolate, vanilla bean, vanilla/raspberry, and strawberry shortcake), with just basic "happy birthday" writing, 10" for $80.
So NOW my plan is to order a cake locally and bring it with us on Tuesday (we only live 2 hours away, probably should have thought of that first!

)
Anyway, just wanted to report back for anyone curious about cakes from the Swan & Dolphin.