http://www.naxja.org/forum/showthread.php?t=939460
Above thread on NAXJA shows a super cheap budget build I did on a teens XJ to fit 245/75-16 MT/R's on stock KJ wheels. XJ works well for cheap and looks good. You can do it super cheap if you shop around or go for a RE lift that is easily upgradable as you get inchitis.
OME can't be beat for overall quality in a small lift but you pay the price in $$ cost.
I think the best bet is to shop on NAXJA in your local section for used parts including bumpers. XJ folks are constantly changing and upgrading so you can often find great deals on used parts that are in fine shape. Keep the questions coming here and us XJ owners will help any way we can.