Many credit unions use UBS, they usually have a book with a set price for the auto and the packages that you want. You will referred to a certain dealer in the Metro area and then to a specific salesperson at that dealer.
The price is usually pretty good, I have never used it, but have used their figures as a bargaining tool. I know several people who have used it and were very pleased with their purchase.
As in any large purchase, do your homework!