I have made a small tweak to my PI spreadsheets.
My PI spreadsheet prices have historically been based on average sell prices across 4 trade hubs (Amarr, Jita, Dodixie, Hek)
For me being wormhole based, Amarr is mildly preferable to Jita (and yes that even includes my stocking of nullsec) as Amarr is well overrepresented as the closest wormhole route, but any of them may be closest.
What I (and commenters) have noticed recently is that sometimes the average of 4 hubs is screwy because (generally Hek) has one or two really bad prices.
So now, I am using a slightly more complicated 'sell' price which is best sell of Hek or Rens and then averaging 'Minmatar', Amarr, Jita, Dodixie.
For those who have not seen the spreadsheet before, it's master is at https://docs.google.com/spreadsheets/d/1lXM8PqU0Tn4EJJ2xRuI7uo55IrZ7MKWJidK9T_bA9L4/edit?usp=sharing
As google docs is no longer reliably playing with eve central nicely, I also have a PDF version linked manually from http://foo-eve.blogspot.com.au/p/pi-spreadsheet-snapshots.html (linked at the top of this blog). The most recent PDF version is https://drive.google.com/file/d/0B1HsU_rOxWl4VHI3YkVjUFJVazA/view?usp=sharing
PS. My last post a fortnight ago was me saying I was rebuilding my Eve setup. This turned into something more involved and ended up being a complete PC re-install from operating system up.