So let's set aside our trade targets Sale and Gray and Carrasco and Quintana, and turn our attention to the FAs.
SoxScout has been maintaining an awesome pitching spreadsheet here. Take a look.
I won't reproduce that considerable effort, but I will provide links to the B-R and Fangraphs pages for each starter, their 2016 baseball age, whether they would cost a draft pick to sign, and the Fangraphs median crowdsourced contract prediction — with the caveat that those estimates tend to undershoot reality by 10-20 percent.
Also, I've included more FA pitchers than I consider aces, but ran out of survey slots before I got to e.g. J.A. Happ. Please correct me if I've gotten any details wrong.
[BR | Fangraphs] Johnny Cueto, Age 30. No pick, 6/$132m, $22m AAV
[BR | Fangraphs] Wei-Yin Chen, Age 30. Pick, 4/$52m, $13m AAV
[BR | Fangraphs] Zack Greinke, Age 32. Pick, 6/$156m, $26m AAV
[BR | Fangraphs] Yovani Gallardo, Age 30. Pick, 4/$56m, $14m AAV
[BR | Fangraphs] Hisashi Iwakuma, Age 35. Pick, 3/$42m, $14m AAV
[BR | Fangraphs] David Price, Age 30. No pick, 7/$196, $28m AAV
[BR | Fangraphs] Jeff Samardzija, Age 31. Pick, 4/$64m, $16m AAV
[BR | Fangraphs] Jordan Zimmermann, Age 30. Pick, 6/$126m, $21m AAV