cost savings of approximately 99.87%.
End-users still have to somehow obtain bitcoins. In a way, Zygna passed on those costs to the end-users. Granted, exchange fees aren't too bad (e.g. Mt.Gox is currently 0.3975% per transaction), and is still much better than PayPal's 8.9%, but if we're going to do the math, let's take the end-user fees into account as well.
Some of us already have Bitcoins, we just need more ways to spend them.