Welcome to 2014. 2 tone paint jobs went out about 10 years ago for good save for a few options.
If you're getting a new truck the easiest way to accomplish that and most economical from initial cost to resale value is to vinyl wrap the portion you want changed. It's durable, easily remove able and if you're doing the lower portion it's like a rock guard for the paint. And maybe color match some fender flares.
I've thought about doing up my truck like the old skool 50-60s models with a white cab from the windows up on a colored body. Prolly look stupid compared to the old trucks though.