absolute cheapest way is to do a front to rear swap. find some 3.5-4" lift springs like rubicon express for the front, then take the stock front springs and move them to the rear. this will give you 3-4" inch lift. throw on some new shocks like procomps and you got a 3.5-4" lift for dirt cheap
edit: i should note that you should be fine on stock control arms if you were doing 31's, but with 33's you adjustable arms is what you will need to push the axles out. especially the rear axle. you will need extended brake lines in the rear. for the front you can unbolt the mount that holds the brake lines in the fender and pull out a ton of excess line out. I use to have a zj with 6.5" lift and stock lines up front with no problems.
you will need longer sway bar disconnects and end links to match the lift height. If your not a do it your selfer and dont want to spend all the time doing this then a complete out of the box lift is probably what your looking for. in that case i would stick with rubicon express. skyjacker and pro comp are poor quality products and their springs sag pretty bad down the road.