How big are we talking? I know Walmart has a wonderful line of pots called Tramotina tri-clad, but the biggest one I think is 22 qt for $79.99. I know Walmart you ask? I have a Bluestar and so far so good. Scroll down there is a thread on these pots.

I was hoping for double or triple the size of my current 18 quart one. But it turns out that as the get bigger they get wider than my stove will allow (a raised enamel edge which research tells me will be harmed by the heat is only far enough from the burners to safely allow a 12" wide pot).

I took width measurements at my local restaurant supply stores (which had pots up to 80 quarts). I see even bigger ones at these links:
http://www.foodservicewarehouse.com/stock-pots-stainless-steel/c30952_30230-151.aspx
http://www.kitchenfantasy.com/shopping_cart/stockpots.html