50-55K for a car with 30-40K miles is an absolute rip off. You need to follow autotrader and see the pricing trends.
The 2011's are going from 47K-55K. I would not pay over 54K for a 2011 under any circumstances, with the exception of the UltraSonic Blue color (their limited edition color that is IMPOSSIBLE to find).
Best deal I got on a 2012 was 57,000 and the car had 62 miles, but had red interior which I couldn't stand.
The 2010's are in the mid 40's now.
The 2008-2009's are anywhere from the high 30's to low 40's just depending on the mileage and condition.