A lot will argue the ego8 and etek3 are on similar levels, although overall the Ego 8 is better, and does have performance advantages against the Etek 3 - such as efficiency and also a LCD screen. Don't forget the Etek is generally aimed at as a PE Entry level marker.
I recently bought my Ego8 for £350, so i'd say £300 is a pretty good bargain! Best of luck to seller