I think the KAW robo tyrants is an outlier in several regards. First, overpay should be calculated as 0.9 * middle since 9.5 is not sufficient overpay for a hat priced at 9.9. That would really be ~9 after overpay. It probably needs an update anyways since there is a current week-old b/o at 9 - http://www.tf2outpost.com/trade/16471289

And honestly, even 9 might be an outlier given the month old b/o at 8 - http://www.tf2outpost.com/trade/15956341

I'd say that 4.9 and 9 are probably outliers unless you can show some more sales near that high end. But 9.5 is definitely too high given two other b/o's at 9 right now.

http://www.tf2outpost.com/trade/15769529 - c9 fed + 3 pure ~6.6 - http://backpack.tf/id/76561198066372570?time=1385193600

http://www.tf2outpost.com/trade/15413627 - TW sam ~6 - http://backpack.tf/id/76561198066372570?time=1383724800

KAW robo tyrants would be ~9

Sales at 4.9, 6, 6.6, 7.7, 9

Most b/o's at 9, one b/o for 1 month at 8

Perhaps high and low sales here are outliers. Your range of 7.7-9.5 is definitely too high.