When Kris gave me the Winter 2009 issue of Martha Stewart Weddings I thought the cover was stunning:

A plain 3 tier white cake from Marks&Spencers can be under 200 pounds.  The fabric butterflies are less expensive than I imagined as well.

But say those butterflies are a bit too realistic looking for your taste, you can also put a little DIY time in to create some beautiful origami versions like these:

(from here)

Here are a variety of butterfly origami instructions. You would just have to attach a bit of wire (or an unbent paper clip) to the butterfly and stick it onto the cake.

A butterfly cake would fit in beautifully in a casual outdoor wedding like this one (from Snippet & Ink)

Tags: butterflies, diy