How much of this needs permits? inspection? If you rough in the trench work and/or plumbing without permits and fly under the radar, be sure to check the codes in case you get popped. That way if you do get popped, you arent having to redo the work, just pay the price. With that said, renting a back hoe and getting dangerous with the trenching and leveling and compacting could save you some dough, but as previously stated.....how much? Is it worth it? How quickly is it getting done? You might be better off trying to save money building the structure....framing, pulling wire and whatnot.