Why is there such dissimliar information in PEAuction and the ingame auction. Some auctions arent in PEAuction, some are. Some of the PEAuctions are outdated, some arent. Shouldnt the two be exactly the same on a consistant basis?

This can't be as peauction has no info on buyouts.
Also peauction removes outliers from the result whereas the ingame auction does not. This leads to oddities in peauction (e.g. check out the price for an opalo).
It is my impression that both peauction and ingame just take the average of the markup. For normal items this is ok, but for stackables it should probably be an average of the sum of (transaction # items * transaction price)/ total # of items
That does give larger batches more weight in the calculation.
Otherwise it is easy to steer the price with small purchases with high markups.
(of course this is less of an issue with peauction due to the filtering of outliers).