I recomend against crimp lugs, as they tend to detirorate quickly. Unless you have a proffesional crimping tool, it's also easy to over crimp, or crimp them wrong, and then it's even worse. They're also open, so the connections tend to corrode. I recomend you solder all the connections, then either wrap in electrical tape, or even better, use heatshrink tubing. If you do it this way, the wiring will probably outlast the truck.
As to the $100 vs 300, the difference is probably in quality. The cheap one likely uses cheap wires and connections, and will not last. The more expensive one will most likely use a thicker insulation, and better connections. The cheap one may also not have all the options, and could fit poorly. I once rewired a vw bug using a cheap harness, and the harness fit very poorly. Half the conectors were either to short, or where in the wrong place, so I practically had to rewire the rewiring kit! Since then, I've done my own. Most of it is easy, probably more so with the older trucks. The tail lights are very easy, just 3 wires, and the engine harness isn't much worse. The only thing you'll have a bit of trouble with would be the dash harness, and even then, it's just a matter of tracing the old wires out, then replacing them.
~John
