I would use a loaf pan. then ice it and do the decorations. do the decorations in fondant. ie gold and brown
The purse cake I made is similar in shape and I used a loaf pan. (it's in my pics). I stacked 2 on top of eachother and then rounded off the top corners a bit by carving & then covered in fondant. I was totally intimidated to try & make a purse cake, but it turned out that the purse was the easiest part of that cake!
That picture looks like everything is buttercream except the trim of the purse? I also want to try to make a purse cake for my friend for her birthday but I want it to be buttercream and not fondant. I've been searching up and down the forums too!
Instead of a loaf pan I baked a rectangle pan then cut it so I had three layers to stack up. I was also able to have the bottom piece slightly larger than the top piece so I had very little cake to cut and throw out. Here is a pic of the one I did, hope this all makes sense!! Good luck and of course we would love to see it when you done!!