Just a heads-up: Nachbar ended his contract with Dynamo Moscow, he's an unrestricted free-agent now. Personally, I'm not interested on him, but a propos, I'll paste here something I wrote in the comments section of a fanpost:
I believe the Celtics should look at the european leagues in the free-agency market. There are always some good players available to grab there. Off the top of my head: Will Bynum, Stephen Jackson, Bruce Bowen, Udonis Haslem, Anthony Parker, José Calderon, Andreas Nocioni, Luis Scola, Raja Bell, Nocioni, James Singleton; or in the past guys like Bill Laimbeer, PJ Brown, Mario Ellie, Antonio Davis, Darrell Armstront, etc.: all of them were free-agents in Europe before joining the NBA.
I'm pretty sure there are some players currently in Europe that are legit NBA rotation players. You can pick from guys with NBA experience like Childress, Delfino, Nachbar, Pargo, etc.; former NBA busts who have developed their games like Marcus Haislip or Rakocevic; undrafted free-agents like Bourousis, McIntyre, Romain Sato, Austin Nichols; or guys who were drafted but are still to join the league, like Fran Vasquez, Andersen or Lorbek.
I think it's stupid to limit yourself to the current crop of NBA players; most of those guys (and others I didn't cite) are good enough to play in the NBA and maybe you can get them for cheaper.