harnesses need to be secured to a rollbar. there is nothing factory in the truck that the harness can be attached to.
it wouldn't be worth having a rollcage built and installed just to mount a $40 harness to it. now, having a rollcage is completely worth it's weight in gold and would obviously be a great thing to have, and as an extra you would have a great place to mount a harness. but it's not really logical the other way.
i would expect a custom (cause they all would be) rollcage for a ranger to be in the $500-$1000 range.....unless you can cut, bend, notch, and weld DOM tubing yourself.
1995 Ford Ranger XLT | 4cyl | 5spd | ext. cab | 2wd | Tuff Spray-in Bedliner | Pioneer DEH-6500 h/u | Kicker KS525 5.25" in doors and rear panels | PPI 4480 4 channel speaker amp | Profile BA400 sub amp | JL Audio 10w0