You want a recent example?
This week on eBay the same seller had 2 different 1915 CJ Sam Crawfords that sold via auctions that ended a few minutes apart.
One was an SGC 60=5 that looked a lot better than the grade. The other was a nice PSA 6 (though it had some weirdness on the reverse).
The cards went for almost the same price (so much for the PSA "advantage").
Links:
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT
Cheers,
Blair