is this an alright price i seen one there recently dont know the power it was an electric hybrid type bike.
But perhaps to give you a more constructive answer;
Gather what more information you can about it and maybe post to the
Electric Bike subforum here. Bear in mind this is largely an American forum - so you'll have to consider that when talking about our $AUD dollar values.
I'd see what they retail for new also.. and ask what the risks maybe buying secondhand eg; battery life. Bargains are generally more certain when you know your product a little more beforehand.