Here's one tip that a friend of mine does that works every time.
1.Go to a Ford dealer.
2.Take a test drive in a new 5.0 Mustang.
3. Drive it directly into the Chevy lot and park it next to an SS. (say you need to see them side-by-side for a proper comparison)
4. Wait for the Chevy salesman to come out.
5. Let the 2 sales guys duke it out.
You will get all sorts of extra offers like free tank of gas, oil changes for life, dealer cost plus $100, etc, etc. You will find out very quickly how low they really can go on the price.
He does this with trucks every 2 or 3 years, even though he is a die hard Ford truck guy. He'll drive a Silverado over to the Ford lot or a Dodge.
'94 Z28, 414" LT1, 10.15 at 133.65 N/A
'14 1LE, NPP, 12.991 at 109.40