There are many way to add IFS to your truck. Like Robin said, cheapest isn't always the best way to go. I wrestled with the same thing when I was looking to do mine. I finally went with the front end from a '79 1/2 ton because it was relatively inexpensive (I have about $500 tied up in it including the cost of rebuilding it and having the crossmember narrowed) and I could do most of it myself. Although it's along way from being road ready, it's coming along pretty good. What ever you decide on make sure you do your homework. Good luck!
Robert C.
If it's true what they say, "You learn from your mistakes,"
I'm a Genius in the making.
1950 3600