This is more of a addendum to the previous post, rather than a self-standing post. So if you didn’t read the earlier treatise on podcast advertising figures, then check that entry first.While i thought i had carefully crafted my logical fiscal analysis of the podcasting issue earlier, i realized one thing I had missed while talking to a fellow entrepreneur about the concept of file serving and storage mechanisms for consumers. The cost is not in the storage, its in the bandwidth. The bandwidth was a factor I considered from the getgo, but had always attributed storage costs to each individually delivered podcast, when in fact its a declining cost.Think of it in basic accounting terms, if you’re going to ammortize the cost of the land (the hard drive space), you can do so over the lifespan of the property (each podcast). So instead of factoring a fraction of a cent per download ($.15/GB storage on amazon S3), you are really looking at it as a declining cost. So the initial podcast serving is the most expensive one, but everyone thereafter is subsequently cheaper to deliver (note these calculations do not account for CPU cycles or stuff like that, as I’m not even sure how to measure those).So as a result of these amortizations of costs, the storage costs are spread out across each delivery, so your costs per might go from $.005 to $.003 to $.002, which may seem like a whole lotta argument over nothing, but in fact adds up (think a million times). With these renewed figures in hand, podcasting becomes a more appealing medium for a broadcaster as his/her costs are no longer fixed at a certain fee per ad (which would’ve necessitated the CPM to be high to profit).Stay tuned for more posts this week as I will be opening up more of the details on castvertising.com, and maybe giving you guys a peek behind the curtains.