I assume titanium is better than stainless as far as leaching goes? With a quick search I could find titanium pots (actual titanium, not coated) up to 5L. I have a few on hand for backpacking, but I've never thought of using them for routine cooking... but this thread has got me thinking. I use cast iron for most purposes, but not for sauces or soups.
I can't imagine a stock pot size would be cheap.