From most of the polls that I have seen on this site, if anyone else were to be traded, Jason Richardson would ideally be the one to go. 

As it stands, he is the starting shooting guard for the team.  He is not a great defender, but is a terrific offensive player.  He can shoot the 3, post-up guards, run, and is one of the best dunkers ever.  He essentially could step into the offensive void left by Marion, and, I think was better.  Not defense, though. 

J-Rich's contract has 2 years left for a total of $27,777,777 (according to Rotoworld). 

The most commonly mentioned suitor for J-Rich has been the Minnesota Timberwolves because they have been athletic wing scorer who can also provide some star power - especially since Rubio might not come over.  They don't really have any players to trade either.  Well, at least not any they would give up.

What they do have is what is likely a mid-high lottery pick for 2010.  The T-Wolves also got an expiring contract player in Etan Thomas.  I'm no expert on the salary trading rules of the NBA, but I think a little something like this might work:

Jason Richardson, Cleveland's 2010 2nd Round Pick for Etan Thomas and 2010 and 2011 1st Round Picks.

Any thoughts on how to make it work better?  Would Phoenix have to include its 2011 1st Rounder or a bench player like Jared Dudley?

The problem is that the Suns don't have anyone to replace him.  Barbosa is fine offensively, but would be a defensive liability, especially next to Nash.  The free agent market isn't exactly robust either.  The top shooting guard is Ben Gordon who is about to sign a hefty deal with the Pistons.  The best of the rest include AI, Dahntay Jones, Anthony Parker, and Marquis Daniels.  AI is a definite NO.  Jones and Daniels are not starters.  Daniels doesn't shoot the 3-ball all too well, either, and his defensive isn't great.  Jones is known as a fine defender, but isn't much offensively.  Parker is decent, both offensively and defensively.  He can shoot the ball, dribble, and defend.  All great, except he's 34.  He's already starting to diminish, as most do at that age.  Still, he's the best all-round option.  And if the Suns plan on contending this year, they might as well do it with a bunch of old guys (Nash, Parker, Hill).  Barbosa and Tucker could spell him off the bench, so I'm not too worried.  He wouldn't cost much at all either.  Say, 2 years for $5-6 million max.