Modified Mel's Mix

I've got the 1st edition of SFG, and the recipe for soil is, shall we say, daunting for beginners.  Apparently in the 2nd edition of SFG, the author Mel recommends a mix of equal parts peat moss, vermiculite, and compost.  I found mention online of a modified version of "Mel's Mix" that recommends half compost, and quarter parts peat moss and vermiculite.  That's nicer since vermiculite is fairly expensive locally ($35 for 4 cu ft).  You can get vermiculite for insulation, but I have yet to assuage my concerns of it being "garden grade".