More on Visual Studio Team pricing estimates
I think you are wrong when you say that nobody will really pay for the full price, that that is retail, etc. This is exactly what prices are for, or setting how much people have to pay for the goods. Simple is beautiful. So, please, keep it simple.
Also, as far as I understand, the problem with the prices is that they do not scale. A small independent consulting company with one to two developers should be able to get the product for a lot less. On the other side, a company with 1000 developers that will use the whole capacity of the Team Server should probably pay more.
Also, unit testing and some other selected features should be on all packages.