Car manufacturers put their prices on their websites so you can look on Mazda's Thai website. They will show the basic list prices, which are the same at all dealerships, with some leeway in whatever options, deals etc. each dealership is willing to provide.
On that page, go down and click on the models and you'll see the prices and the 2.0C is indeed 989,000, with the others over 1 million. It's then up to your wife to see what she can extract from the dealer. Often it's just a lot of extra freebie options rather than a dis