Was just cruising around the Cortex and I stumbled across Ideal808.com which is apparently selling boxes of Serenity cards at $59.95 per, the cheapest I’ve seen them yet (and less than I paid for mine, gorrammit).
They also have the 2005 San Diego ComicCon Inkworks promo sets — promo cards for Inkworks card series Lost, Alias Season Four, Buffy Men of Sunnydale, Charmed Conversations, Sopranos Season One, and Serenity that were handed out at last year’s con — on sale for $4.95. They ship worldwide.