If it's in decent shape that's a pretty darn good price, especially if it's with mags, case, etc. Figure 10 rnd mags sell new for $10 each and hi caps at around $30-35 each. New ones had a black plastic case while older ones had a grey plastic one. You can tell when it was made by the two letter date code on the slide.
A B C D E F G H I K
0 1 2 3 4 5 6 7 8 9
So a date code of AG indicates it was made in '06.