If you can spend just a little more I recommend piecing it together to keep costs down but increase quality.
I run OME HD leaf spring packs in the rear and net you +- 3" of lift. They also ride FANTASTIC. The more weight the better.
Grab a set of Rough Country 3" springs direct from RC. Ask for the Jeep Forum Discount.
Grab a set of JK Rubicon shocks ( the red ones) for about $50 as pull offs when somebody else goes bigger. They're perfect for the XJ at 3-4" of lift. All you need to do is push out some sleeves for your bar pins from the old shocks.
Pending your Jeeps age I'd throw in a new steering stabilizer for good measure with those 31's and possibly a T-case drop. Pretty much ready to run some light trails and have a good looking DD at that point.
Should be able to have a very nice riding trail/DD rig for ~$350.