you can save a lot if you can find good condition used WJ arms in the junkyard. but new ones aren't crazy expensive so it's all about your time vs your money.
the 3" kit straddles the line, where the 2" kit affects the suspension geometry very little and the 4" affects it a lot. some kits skip the arms and track bar completely. to do this you need to adjust the lower arm shims as we've suggested with the WJ arms (same length as stock, just curved and infinitely better built). without a track bar your axle will shift over to the drivers side a bit. most all kits seem to skip the brake lines which is a bit scary to me. it is true that you can jack it up 3" higher with coils and AALs and call it a day. it'll be 3" higher for sure and probably work ok in the dirt, but you won't be happy with it for long if you drive it every day. If your budget really is tight, maybe scale back the project to be a 2" budget boost (spacers, WJ arms, longer shackle out back).
don't forget an alignment after it's all said and done.