Mytopo.com is having a 20% off sale right now.  Use code Aerial2012 on checkout.  They have always done me right.

The best thing about ESRI's ArcGIS and Google Earth is their updating frequency as a rule far exceeds that of most municipalities.  For where I'm at Google Earth is 2011.  Ironically we have a fly-over from 2012 in house, but this is the exception and far from the rule.

At the rate that agricultural and wooded lots are becoming subdivided it pays to have the most updated aerials.

~CB