Amazon has the McLane 801 [amazon.com] gas powered edger on sale for $289.99 w/ free shipping, lowest price I have seen. Typically it is $329.99. Not a huge drop in price, but it seems it never is on sale and costs about the same or less than 'comparable' big box brands w/ taxes.
Gets very good reviews for performance, subpar for setup and instructions. Most appear to be very happy with it.
I have looked at the big box stores and most of the selections get ok reviews at best but most Amazon reviews claim that this is far superior to those.