At this point, about an ounce and a half. I've only been smoking pipes for a few years though so right now I don't feel confident enough that my taste in blends won't continue to evolve and change over time to cellar significant quantities of anything. I started off smoking aromatics, then was really into Burleys for awhile, dabbled in English blends, circled back to aromatics, and now I mostly smoke straight Virginias and dark-fired British death rattle flakes (1792, Dark Flake, etc).
As much as I'm enjoying my current favorite blends though, I feel like I should give it another year or two just to make sure my tastes don't change again before I start cellaring away pounds of anything.