I have never bought a vehichal from a dealer before and i have some questions about how to lower the sticker price.

I am having a very hard time finding cummins here in MN, i have not found any on any of the dealer websites ive visited and there are only 5 or so on sites like cars.com thus I am looking to buy out of state but perhaps this is not a good thing to bring up at the dealer as they might think they have an edge on you. I intend to inspect the truck, find everything i can wrong with it, total the repair amount including labor and demand that much off the price/blue book value or i walk out. is this likely to work?

I hear state auctions are a great way to find cars but for the life of me i cant figure there websites out.

thanks