I think a locker is a bad choice for a 2wd daily driver. You will have to endure the clicks, clunks, clangs, tire squeal and get very little in return. The only time you're gonna love that locker is when you're crossing a ditch that lifts a wheel.
In my opinion, the cheapest improvement for a DD is the Ford Trac-loc limited slip IF you want to keep your existing rear end and have the know-how to do the install. The next best would be a junkyard complete rear swap for the Torsen limited slip found in the FX-series. And finally, an upgrade to an 8.8 Explorer axle which gives you a lot of options (I personally like the Detroit Truetrac LS).