Too complicated... keep it simple, or the client will feel like you're trying to pull a fast one on them.
Break it down by functional items ONLY -- e.g. e-commerce, user profiles, shopping cart, database backup, search engine optimization, whatever -- because there are the only things that they can translate into $$$ in their heads. No one cares that there's a database, or how complicated (or elegant) it is, or how their site is built to some magical spec / standard that doesn't affect them in any way, shape or form. I don't even mention any technical aspect at all... not even the technologies... because it doesn't matter.