If you're a USAA member just log into USAA.COM
Look for products-> car buying services -> build your vehicle
It's easy and I had 3 offers well below MSRP. Two of the offers were below invoice.
Two of the three dealers would only honor the price for vehicles on the lot or vehicles that you ordered through them. The dealership I used honored the price on a Jeep that they had to transfer from another state. I did pay part of the transport cost but that was negotiated up front.
It's the only way I will buy another Jeep... On the other hand I got better pricing on a new F150 by using my X plan through work so its not the end all be all of new car buying.
There was also an option to buy a used car through USAA's car buying service but I did not look into this
I hope this helps