No, you’re not being taken for a ride. There is a good post on this here:
With solar, the pricing is per W. In both cases you getting a 15kW system, and it will take up similar amount of roof space (the 400W panels will take up slightly less space overall). The 400W panels are more expensive per watt.
I would suggest avoiding the 400W panels. You are paying a lot more, for a little more efficiency. Unless you are short in roof space, efficiency doesn’t really matter. You should also consider the LG Neon 2 panels, which are very good value.