I too am in an area where people do have a lot of money. The only time I under price a cake is when I havent done it before and Im not sure how it will turn out. I recently did a wrestling ring and it was a 10in square cake and I only charged the man $65, because I had never done one before. $65 dollars for that cake would have been underselling it.
I am in the poorest part of NC but a cake like that with the detail and the materials, I would hav enot sold it for less than $85. When I just started out selling my cakes to other people besides friends and family I was giving away my cakes too. If you go ahead and bring your prices up with the work you are doing trust me @ $85-90 you are doing them a favor. The cake looks really nice by the way and keep up the good work. I go by my serving sizes for my base pricing. Print out the wilton serving chart and just adjust it to your area for how much you are going to charge pre serving. Right now Im at $2 a serving so times that by 32 would have started them off at 64-65 dollars.
BUT DAMN THESE PEOPLE UP HERE HOLLERING 100-200 DOLLARS I HAVE TO MOVE QUICKLY