Obviously you will have lot of choices and here are few of my recommendations,

Places to buy

1. Hot Breads

Name  : Hot Breads
 Phone :

Comments : They sell by Pounds. Have lot of themes. No Custard filling though. 

2. Safeway

Name : Comments  : They sell the cake not buy Weight but by  “SHEETS”

Quarter Sheet - Sufficient for 25 Adults

Half Sheet      - Sufficient for 40 Adults

Comments : They have lot of themes available.  You can add Custard filling for couple of dollars, would STRONGLY recommend that.