This is actually two suggestions in one.
Have player achievements appear on their player page. Things like league MVPs, years in which he led the league in a stat, ASG appearances, etc. It would give the players just a little bit more personality and you'd be able to see all of their accomplishments at a quick glance.
Then you could also tie those achievements into a slight merch boost. I think that would be a little realistic too. I mean Dwight Howard hasn't played a single game for the Rockets yet and is in the top ten list of hottest selling jerseys in the NBA. You could also tier the merch boost to whatever league they got the achievment in. So league V achievements would only mean a few extra dollars while upper tier player achievements might result in $100 - $300 each depending on what the achievement is.