I've gone and adjusted all my listings ending post 7th April to reflect flat rate parcel under 500g cost of $6.95, plus 15c for satchel.  Once I have more of a gauge of eBay C&S fees I'll start pricing accordingly. 

However, I have a listing ending after 8th April with a bid that I'm just gonna have to wear the postage cost difference.  Gonna be stuffed with any buyers who pay post 7th April too, and I highly doubt that AP will take any of this into consideration. *Sigh*