Edmunds.com is a great way to see MSRP and "Invoice" pricing as well as average sale prices in your area. I figure out what I NEED and what I WANT and make a decision based upon price. After I figure out the exact truck I need, I email the internet sales divisions of local dealers. No high pressure sales tactics, no going back and forth with the manager, no other games. I submit my request and await their response. I have a pretty good idea what to expect based upon my research. Some guys came in WAY high, sometimes you get a surprise and get a lower price than you expect. I get ALL the details nailed down before I step into the dealership.
The only problem with ordering a vehicle from the dealer is that you can't be 100% certain when to expect delivery and therefore its hard to get the best rebate. You would have to do some research ahead of time and figure out how long to expect to wait to take delivery and try to time your purchase for expected rebates.
Best of luck!