Um, a few guys on that list won't even be free agents. Greg Monroe and Evan Turner are still on their rookie deals and their teams can decide if they want to pick up modest extensions (forgone conclusions). Gerald Wallace as a player option for almost $12M and won't turn that down to make $6M for us. I doubt he turns it down without getting a deal for at least as much for a few more years. Hibbert, McGee, Mayo and Batum are restricted free agents, so they'd need to be overpaid to get their current teams to let them go. Landry Fields is the only true free agent, and I wouldn't mind him, but I think we could find a better fit.
***On a side note, I'm not sure why so many people are pro-Hibbert. His game doesn't fit with the offense that Scott runs, doesn't fit with Kyrie's strengths, doesn't fit with Andy or Tristan, or anyone else. Yes, he's big. Yes, he can walk without falling down. That's the extent of his appeal. It's not fantasy rosters being built, they have to click on the floor. Hibbert isn't a pick-and-roll player (like Kyrie needs in a big man). He's not a pick-and-pop guy either. His mobility is average, at best, and will only decline (pretty quickly) as he ages. Brook Lopez and Spencer Hawes are restricted free agent centers that would fit the offense MUCH better and JaVale McGee is a restricted free agent that fits the defense MUCH better. I just don't get the Hibbert love.