All grain with 55 lb sacks is the way to go (I think I pay 88 cents per pound for Best Malz and MFB Pils sacks at my LHBS). Buying a pound of hops from hopsdirect is also going to save you a lot of money.
Everything else (yeast ranching, canning starter wort, etc) is worth it, but has less return.
+1 on the full sacks of grain if you can store/use them.
There are lots of little tricks (like brewing 10 gallons instead of 5 to save pennies on propane or growing your own hops) that aren't going to be appreciable.
I'd recommend acquiring the important equipment over time when you can find it cheap. When you do spend money, focus on the biggest bang for the buck in quality (i.e. control fermentation temperature before buying a draft system).
If you really want to control the cost per batch - brew the cheaper beers now while you're poor. Get good at it, then when you can afford it move up the line.