I buy my boxes from www.brpboxshop.com. I think they also have some cake boards but never really looked at them. I can usually get my boxes in 2 days and they have free shipping.
As for boards and supplies in usually buy them between www.globalsugarart.com and www.sweetwise.com. I like both theses stores because once again I can usually get my supplies in 2 days.
I purchase all my cake boards, fondant etc from fondantsource.com, I get my boxes from webstaurantstore.com
Both sites have good prices and quick shipping.
I will have to check out brpboxshop.com and see what their prices are like. Free shipping would be fantastic.
If you google coupon codes for fondantsource you should be able to find a code to use for 10% off. I have been using the code, welcome, to get 10% off orders.