Well, you could also have some sort of weighting that's inversely proportional to posting fees, in order to even out territory revenue on these posts (and incentivize lower posting fees).

With even shares, there's a little incentive to have higher territory fees, because you get an equal share of zaps regardless of your fee, plus your entire fee (or 70% of it, to be more accurate).

There would also be the more ideal version of attributing zaps to a specific territory, if the reader found it through a specific territory.