If your handy with your skills just pick up a pair of Milwaukee electric sheers (about $169.99) and a couple of old dryers (about $10 each) and cut your patch panels out of the appliance sheet metal. There are a few "tricky" spots on an FJ that may require a beginner to buy a replacement panel, but for the most part these things are a body mans dream. Most of it is flat panels. Worst case scenario, if you have a buddy in construction, that owns a flashing break, you can make your own fenders. If its corrugation you need, such as the rear fender wells or the bed floor. Source that from the bed of almost any pickup at a salvage yard. Better yet get it from a Toyota truck, that way you can still say "its Toyota factory corrugation". Just don't tell the purists what I just told you. I think they're about ready to slap me as it is.
FJ40 stuff is expensive to say the least. You've already commented that your not building a show truck, if you take your time, and try to keep the original body lines, at 55mph no one will ever know that your rocker panels are actually the sides of a Kenmore washing machine, and you'll still be able to afford to put gas in it because you didn't spend hundreds if not thousands on body panels.
"throughout the history of 4x4s only a few earned the right to be called lengendary. The original FJ40 Toyota Land Cruiser is one of the few" - TLC Icon