If forced to choose only one, it would be 44 Mag. Better would be 45 Colt. Nothing at all wrong with .357, if that's what you want. If you cast your own bullets, cost would be primer and powder, less than five cents a round, or call it 10 cents a round really high siding it with the current state of prices. Cost of the brass is a one time thing, and prorated over it's life, if loaded reasonably, is hardly a factor. If you have to buy your lead for casting, then that is a factor. Initial start up cost for casting, along with buying new guns, and loading equipment, can really stretch a budget. For most of us it happens over time (years).