IMO page authority doesn’t matter when selling links.. obv it needs to be considered when acquiring, but this should be part and parcel when doing your recon to see where you can get relevant, authority links from. Surley you have been considering page authority in the past when brokering links?
as for the Seomoz tool, it’s just a jumped up version of siteexplorer from what I could see, altho it does offer some added functionality/bells and whistles [siteexplorer closing soon, queue the seomoz guys entering the fray to make some $$$…]. One can probably write a few scripts to do the same job for free using the SE APIs.