regular maltodextrin and dextrose are actually really cheap when purchased thru a brewing supply store...
I've seen a lot of recipes that call for dextrose online... just a small amount. Reading the back of my jug of Hammer gel, it calls for Maltodextrin, grain dextrose, fruit concentrates (I'm thinking a little scoop of fruit juice from concentrate for the 'all natrual' hammer stuff, or coffee/italian soda syrup for more exotic flavors) and amino acids. Correct me if I'm wrong, but can't you get amino acids via health food shops? I'm thinking Bragg's Liquid Aminos would work, but I'd be VERY hesitant to use that as it's got that STRONG soy sauce flavor.