The internet is your friend. I've purchased my last two cars via the internet route.
For a new truck, check out:
www.edmunds.com Find out exactly what you want. Find out exactly what MSRP is and what invoice is. From there, you'll get a "True Market Value" number.
This "True Market Value" will probably include a holdback fee (.02% of MSRP) and a "advertising" fee. You can't get around either.
Once you get a handle on what the truck REALLY cost the dealer, come up with an offer that acceptable to you. Personally, I don't like giving the dealer more than a 3% profit on their vehicles.
If you're ready to deal, fire off the "email the dealers" not option, and wait for the phone calls to come in.
Just remember that dealers make their money by:
-Forced holdback on the vehicle. They're getting about $900 already on hold back.
-Trade in. If you have a vehicle that you want to sell, do it privately. If not, you'll get hosed by the dealer.
-Finance. If you belong to a Credit Union, or another other non-profit agency, get your auto loan there. They can not be beat.
-Price gouging. They will up the price on you.
Be upfront, let me know your deal, let them know you know how they make their money, and tell them you're looking for someone who's willing to "push tin". IE, just to move a truck.
Try $100 over invoice, and work your way down. Depending holdback, they are already making $1000 on you.
Never bought used, so I can't help you there. But, you can search for used vehicles in your area on:
www.autobytel.com Again, price of the vehicle will depend on what the dealer bought it for. Unfortunately, unless you have a friend at the dealership, you'll never know what they paid for it, so you'll never know how much you're being gouged.
Blue Book Values don't mean a whole lot. They give you an idea, but that's about it.
Hope this helps! I had a blast getting my VW Passat and my Chevy Tahoe via the internet. The best part is you don't have to deal with dealers!