Nissan's Destination Frontier is an example of how you can do it on the cheap. The entire setup here can be had for less than $40,000 if you start with the most basic Frontier: an S trim with a King Cab configuration, rear-wheel drive, a four-cylinder engine and a five-speed manual transmission, which starts at $19,290.
However, the build you see here uses a midgrade $30,240 SV Crew Cab model with four-wheel drive plus the more powerful 4.0-liter V6 engine and a five-speed automatic transmission. It also has the $995 Midnight Edition appearance package.
The most important thing you can add to a vehicle for off-road durability is tires. Here, Nissan added an excellent set of 33-inch Nitto Trail Grappler off-road tires wrapped around 17-inch American Racing wheels.