It really depends on what brand you are buying. I got my "$31k" F150 a few years ago for $26k without the company discount. Fords are heavily discounted from MSRP and that's just the way they've always been. How great of a deal you will actually get with the company discount will really vary depending on the manufacturer.
As someone else pointed out, financing will affect how much you pay the most. Credit unions are probably the best place to go for auto financing(unless the dealer has a special zero percent thing going on).
Also, dont negotiate with the dealer using a monthly payment. They will just play with the numbers like another company I know of... Come in with financing beforehand. Do your research and you could save some serious beer money.