AI'm going to be making a belle Barbie cake. I was wondering if anyone knows where I can order a topper for that. All I can find is ones for individual size cakes. Also how much should I charge for this type of cake?

Are you going to make it a doll cake with Belle's body the cake?  If so you could always use the barbie type doll and insert the whole doll in the cake. Just make sure to wrap the legs and body good in plastic wrap.  It actually becomes a toy for the child afterwards.  I made the mistake of breaking the legs off the first time I did one and the child was so upset.   YIKES!   I have charged between $75-$90 for one of these dolls. Just depends if it is buttercream/ fondant and how much detail.  I have a couple pictures in my album if you want to take a look.   HTH