I am in need of an acrylic/lucite box sturdy enough to hold a three tier
cake. Perferrably 12x12 and 12 to 14" tall. Can someone please tell me where I can get this?

I don't know what lucite is, but this is a super cheap similar size box to the one you are looking for, it's called LEKMAN, it won't let me see it properly on the US Ikea website, although it is there, sells at $9.99, but here is a link to it in Spanish.
http://www.ikea.com/es/es/catalog/products/90059618