Top Down, now is the perfect time to buy the Mustang you want. I just bought my 2011 at 49. I figured that I needed to do it now because, at 6'7", I may not be able to get in and out of it for too many more years. My wife and I are on the "one car payment" plan. If I didn't get it now, it would be 8 years before my turn to get a car comes up again. I thought 57 would be pushing it after years of competitive basketball have taken a toll on my knees.
Bottom line, go for it. If you can't quite afford a 2011, Ford dealers in my area are highly discounting the 2010s.