That's about right. According to VCP (vintagecardprices.com), PSA 7's have sold anywhere from $450 to $775 since late 2013 with most in the $600-$650 range. The lower dollar prices were generally for those cards with poor centering (despite the PSA 7 designation). The $775 price tag was an anomoly in my opinion (it looked like a 9). Only two SGC examples in the exact same grade have sold in 2014, and they were $480 and $429 respectively, and both had slight left-to-right centering issues.
Hope this helps. Here's my raw example, which has some paper loss on back, rendering it a G/VG, despite the great-looking front. I got this one for a little under $200:
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http://imageevent.com/derekgranger
Working on the following:
HOF "Earliest" Collection (Ideal - Indiv): 250/346 (72.3%)
1914 T330-2 Piedmont Art Stamps......: 116/119 (97.5%)
Completed:
1911 T332 Helmar Stamps (180/180)
1923 V100 Willard's Chocolate (180/180)