£279.99 sounds about right to me. Clear daylight between it and the Vita, no other true next gen competition for a little while at least, plenty of room to budge on price should they need to, a controller that surely has to add something extra to the cost. And all still well under the £300 mark.
Problem is they don't have the games to make me think it's worth any amount of money, not yet anyway. Don't think the more hardcore gamers will forget how they would often go many, many months between Wii releases they actually had any interest in playing.