Here is an interesting vehicle from Goblin motors. The Rampage as they are calling it, is a traditional delta trike platform( one front wheel, two rear) built off the new Rans Trizard trike. It is basically another shell that goes over an existing bike. Very good design for stability at high speeds. Delta platform trikes are more stable at high speeds than tadpole designs, but do not handle as well. Conversely a tadpole design is better at cornering, but tends to wag their tails at higher speeds. Obviously this is a generality and several designs of both have been built that take care of those problems. Not having seen any top views though, it is hard to tell how aerodynamic it is from the pictures, but does show a (lunatic fringe) streamliner at the bottom of their page that this was designed after. The 100% aluminum clad side paneled velomobile is said to start at $7295 US.
For those of you looking for a little aerodynamic advantage without the entire bodywork, they also sell rear sectioned fairings for tadpole recumbent trikes. They have side storage pockets and a streamlined rear section for prices ranging from 600 to 1100 dollars or so. It all depends on what you want and how much work you want to put into it.