Time for a new truck, opinions please

[Gigantopithecus]

It's finally time for me to get a new vehicle. My poor DD is slap worn out. I've had it since 2000 and it has served me well, but I need to upgrade. I need a truck for work, DD and part time parts hauler. I've looked around and I've found a few. Unfortunately, none are Fords, I just don't like the F150 all that much, so I'm going the heavy chevy route. I found one that I really like. It's got everything I want in a truck. So here's the deal. It's an 08 Silverado, Crew cab, 5.3l, 4x2. They are asking close to 25k. I'm NOT paying anything over 20k max, 18k if I can swing it just right. Just wanting to get some pointers before I hit the lot, I need all the ammo I can take. I know they'll try to get as much from me as possible, but I'll take my ball and go home if they get too stupid. I mean, it's not like trucks are flying off the lot now anyway. I refuse to pay any kind of "fat" they add to the bill. I'll issue a line item veto on that.
Thanks in advance, your advice is appreciated.