Yikes! ^
USSkoval said it all: Complete 4 inch kits start at about $300. Save your money for an extra month or whatever and do it right.
My budget recipe was:
3" Tuff Country springs front $200/pair
used 4" blocks in the back (local Craig's List) $20 (with U bolts)
Superlift "Scratch-n-dent" shocks from their e-bay store $10 each
Ford superduty shock tower mod: $20/pair.
Didn't get a full 4 inches in front because I leveled out the "blazer sag". For the money and expertise involved, this setup works GREAT.
Oh, if you really flex it out on the rocks, you'll also need:
Front brake lines for an '89+ IFS pickup: $14.99 each
I will offer one other bit of advice... if it's a trail rig, what's wrong with trimming?

If you want big tires before big suspension, don't be afraid of the saw. I ran 35's on my stock suspension for over a year