I haven't graded many cards, but I've done pretty well with a few of them.
Bought ...maybe 1984? 85? Probably for $3
Another I'd had since the 80's
And one picked up a bit more recently from Ebay. Only cost 40 raw.
Of course they haven't all gone that well, most were more like 50s a couple didn't grade, not modified, but miscut or undersize. Not bad overall though.
Steve B