Just because they are on the same platform doesn't mean they will look the same or have the function, or even draw the same buyers. Did you think the Cadillac and Chevy versions would have looked the same? The Chevy version will draw in the Camaro crowd, while the Cadillac version will take the Alpha into a trendier dimension. As for the Buick Alpha, it will remind Americans of the Buick Reatta, which sported its own unique body style and was crafted with an attention to detail, except that it will be RWD. The Buick version will appeal nicely to Americans and the Chinese that don't want a Camaro and can't afford a Cadilliac.
The Alpha will fit into GM's new Core Brand strategy of having a Volume version (Chevy), a well crafted version 2 or 3 levels above Chevy (Buick), and a trendy Version 2 or 3 steps above Buick (Cadillac). Sort of like having the sizes of small, medium, and large. The good news is that GM won't supersize the platform and give it to all it's car brands.
As for your concern about price between the Delta II and Alpha, what does it matter? They are 2 different platforms and one is a FWD, while the other is a RWD. You can buy apples and oranges at a supermarket that are similarly priced, but the fact remains, they are two different types of fruit, the same will hold true for the Delta II and Alpha.
Oh and never assume, you know what they say about that. :AH-HA_wink: