I guess for comparison the cheapest leveling kit from Thuren is $980 that includes front springs, trackbar, and front shocks only. It's over $200 for the cheapest rear shocks.
I think the Power Wagon setup would be a nice option for your truck. $500 is probably not a bad deal, but not really a killer deal either. In the Jeep world it's common to put the Rubicon suspension on a Sport model for the same reasons (small lift and slightly better shocks, etc...) with the complete setup going for $200-$300. Actually just did this for a guy recently....but will say that Jeep Rubicons are way more common than Power Wagons. I would probably offer the guy $300 cash and see what he says. Not sure what the market for this stuff is as you don't see it very often.