Unless you have the parts already, it is really a waste of money to not buy a complete bike. You are going to tell me that you really want the experience of putting it together yourself and having the bike be completely custom to your specs. I appreciate that and believe me I felt that same excitement at some point but it turns to regret when you actually start building it and you end up spending three times as much on the bike as you would have if you had just bought a complete bike.

You don't have the bike yet so you don't really know what you need. Is there some reason why you need Paul hubs? Unless there is a really good reason for this spec you will probably find that a whole bunch of other hubs would have worked just as well for you. You say you want Omniums. They are stiff but the GXP bottom brackets have a reputation for having lousy bearings, plus frankly, they are ugly. Maybe it would be worthwhile to just ride on whatever until you decide that you actually want an upgrade.

This is just a little more than you would be looking to spend on just your frameset. Even if you wanted to upgrade the cranks right of the bat, it would come out a lot cheaper than trying to piece it together yourself.