You might consider these two bikes direct models:
Cafe Express 8
$450 8 speed hub. If your commute is mainly flat and you want comfort and not speed this should be ok. It might give you trouble on the 500km ride with only 8 gears and the sitting position being so upright.
Cafe Latte
$400 24 speed. This would be better for the distance. There are a lot of spokes so minor offroad use shouldn't be an issue and would be better for your longer ride. Less comfortable but not quite as leaned over as a mild road bike.