There's always Cauley Ferrari (I know, I know, F-cars...) the authorized dealer for Michigan. There is no authorized Lambo dealer yet, but rumour has it the Suburban Collection is getting one to go along with their Bentley/RR franchise in Troy. Makes sense since Bentley and Lambo have the same parent co. (VW) and they are just up the road in Auburn Hills.
There are a bunch of independent exotic dealers in Birmingham, mostly on Woodward. There's Birmingham Imports, Auto Europe and I'm sure some others I'm forgetting.
The cars and specialists are out there, but sometimes they're hard to find in Detroit. Good luck.